torbutton/design/index.html.en (d0a98d221) - tor-webwml.git

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add torbutton design dir fr... Andrew Lewman authored 14 years ago	`1) <?xml version="1.0" encoding="UTF-8"?> 2) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	3) <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Torbutton Design Documentation</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div class="article" title="Torbutton Design Documentation"><div class="titlepage"><div><div><h2 class="title"><a id="design"></a>Torbutton Design Documentation</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Mike</span> <span class="surname">Perry</span></h3><div class="affiliation"><div class="address"><p><code class="email"><<a class="email" href="mailto:mikeperry.fscked/org">mikeperry.fscked/org</a>></code></p></div></div></div></div><div><p class="pubdate">Apr 10 2010</p></div></div><hr /></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="#id2945584">1. Introduction</a></span></dt><dd><dl><dt><span class="sect2"><a href="#adversary">1.1. Adversary Model</a></span></dt><dt><span class="sect2"><a href="#requirements">1.2. Torbutton Requirements</a></span></dt><dt><span class="sect2"><a href="#layout">1.3. Extension Layout</a></span></dt></dl></dd><dt><span class="sect1"><a href="#id2976187">2. Components</a></span></dt><dd><dl><dt><span class="sect2"><a href="#id2969623">2.1. Hooked Components</a></span></dt><dt><span class="sect2"><a href="#id2952263">2.2. New Components</a></span></dt></dl></dd><dt><span class="sect1"><a href="#id2962049">3. Chrome</a></span></dt><dd><dl><dt><span class="sect2"><a href="#browseroverlay">3.1. Browser Overlay - torbutton.xul</a></span></dt><dt><span class="sect2"><a href="#id2941767">3.2. Preferences Window - preferences.xul</a></span></dt><dt><span class="sect2"><a href="#id2976170">3.3. Other Windows</a></span></dt></dl></dd><dt><span class="sect1"><a href="#id2977751">4. Toggle Code Path</a></span></dt><dd><dl><dt><span class="sect2"><a href="#id2944154">4.1. Button Click</a></span></dt><dt><span class="sect2"><a href="#id2978704">4.2. Proxy Update</a></span></dt><dt><span class="sect2"><a href="#id2945348">4.3. Settings Update</a></span></dt></dl></dd><dt><span class="sect1"><a href="#id2966553">5. Description of Options</a></span></dt><dd><dl><dt><span class="sect2"><a href="#id2948284">5.1. Test Settings</a></span></dt><dt><span class="sect2"><a href="#plugins">5.2. Disable plugins on Tor Usage (crucial)</a></span></dt><dt><span class="sect2"><a href="#id2965289">5.3. Isolate Dynamic Content to Tor State (crucial)</a></span></dt><dt><span class="sect2"><a href="#jshooks">5.4. Hook Dangerous Javascript</a></span></dt><dt><span class="sect2"><a href="#id2964952">5.5. Resize windows to multiples of 50px during Tor usage (recommended)</a></span></dt><dt><span class="sect2"><a href="#id2977086">5.6. Disable Updates During Tor</a></span></dt><dt><span class="sect2"><a href="#id2937206">5.7. Redirect Torbutton Updates Via Tor (recommended)</a></span></dt><dt><span class="sect2"><a href="#id2937250">5.8. Disable Search Suggestions during Tor (recommended)</a></span></dt><dt><span class="sect2"><a href="#id2937289">5.9. Disable livemarks updates during Tor usage (recommended)</a></span></dt><dt><span class="sect2"><a href="#id2937361">5.10. Block Tor/Non-Tor access to network from file:// urls (recommended)</a></span></dt><dt><span class="sect2"><a href="#id2937433">5.11. Close all Tor/Non-Tor tabs and windows on toggle (optional)</a></span></dt><dt><span class="sect2"><a href="#id2937514">5.12. Isolate Access to History navigation to Tor state (crucial)</a></span></dt><dt><span class="sect2"><a href="#id2937598">5.13. History Access Settings</a></span></dt><dt><span class="sect2"><a href="#id2937711">5.14. Clear History During Tor Toggle (optional)</a></span></dt><dt><span class="sect2"><a href="#id2979251">5.15. Block Password+Form saving during Tor/Non-Tor</a></span></dt><dt><span class="sect2"><a href="#id2979312">5.16. Block Tor disk cache and clear all cache on Tor Toggle</a></span></dt><dt><span class="sect2"><a href="#id2979362">5.17. Block disk and memory cache during Tor</a></span></dt><dt><span class="sect2"><a href="#id2979414">5.18. Clear Cookies on Tor Toggle</a></span></dt><dt><span class="sect2"><a href="#id2979465">5.19. Store Non-Tor cookies in a protected jar</a></span></dt><dt><span class="sect2"><a href="#id2979522">5.20. Store both Non-Tor and Tor cookies in a protected jar (dangerous)</a></span></dt><dt><span class="sect2"><a href="#id2979560">5.21. Manage My Own Cookies (dangerous)</a></span></dt><dt><span class="sect2"><a href="#id2979576">5.22. Disable DOM Storage during Tor usage (crucial)</a></span></dt><dt><span class="sect2"><a href="#id2979679">5.23. Clear HTTP Auth on Tor Toggle (recommended)</a></span></dt><dt><span class="sect2"><a href="#id2979717">5.24. Clear cookies on Tor/Non-Tor shutdown</a></span></dt><dt><span class="sect2"><a href="#id2979772">5.25. Reload cookie jar/clear cookies on Firefox crash</a></span></dt><dt><span class="sect2"><a href="#id2979847">5.26. On crash recovery or session restored startup, restore via: Tor, Non-Tor</a></span></dt><dt><span class="sect2"><a href="#id2979919">5.27. On normal startup, set state to: Tor, Non-Tor, Shutdown State</a></span></dt><dt><span class="sect2"><a href="#id2979978">5.28. Prevent session store from saving Non-Tor/Tor-loaded tabs</a></span></dt><dt><span class="sect2"><a href="#id2980042">5.29. Set user agent during Tor usage (crucial)</a></span></dt><dt><span class="sect2"><a href="#id2980217">5.30. Spoof US English Browser</a></span></dt><dt><span class="sect2"><a href="#id2980310">5.31. Don't send referrer during Tor Usage</a></span></dt><dt><span class="sect2"><a href="#id2980350">5.32. Strip platform and language off of Google Search Box queries</a></span></dt><dt><span class="sect2"><a href="#id2980391">5.33. Automatically use an alternate search engine when presented with a 4) Google Captcha</a></span></dt><dt><span class="sect2"><a href="#id2980471">5.34. Store SSL/CA Certs in separate jars for Tor/Non-Tor (recommended)</a></span></dt></dl></dd><dt><span class="sect1"><a href="#FirefoxBugs">6. Relevant Firefox Bugs</a></span></dt><dd><dl><dt><span class="sect2"><a href="#FirefoxSecurity">6.1. Bugs impacting security</a></span></dt><dt><span class="sect2"><a href="#FirefoxWishlist">6.2. Bugs blocking functionality</a></span></dt><dt><span class="sect2"><a href="#FirefoxMiscBugs">6.3. Low Priority Bugs</a></span></dt></dl></dd><dt><span class="sect1"><a href="#TestPlan">7. Testing</a></span></dt><dd><dl><dt><span class="sect2"><a href="#SingleStateTesting">7.1. Single state testing</a></span></dt><dt><span class="sect2"><a href="#id2981478">7.2. Multi-state testing</a></span></dt><dt><span class="sect2"><a href="#HackTorbutton">7.3. Active testing (aka How to Hack Torbutton)</a></span></dt></dl></dd></dl></div><div class="sect1" title="1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id2945584"></a>1. Introduction</h2></div></div></div><p>
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`5) 6) This document describes the goals, operation, and testing procedures of the`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`7) Torbutton Firefox extension. It is current as of Torbutton 1.2.5.`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	8) 9) </p><div class="sect2" title="1.1. Adversary Model"><div class="titlepage"><div><div><h3 class="title"><a id="adversary"></a>1.1. Adversary Model</h3></div></div></div><p> 10) 11) A Tor web browser adversary has a number of goals, capabilities, and attack 12) types that can be used to guide us towards a set of requirements for the 13) Torbutton extension. Let's start with the goals. 14) 15) </p><div class="sect3" title="Adversary Goals"><div class="titlepage"><div><div><h4 class="title"><a id="adversarygoals"></a>Adversary Goals</h4></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><span class="command"><strong>Bypassing proxy settings</strong></span><p>The adversary's primary goal is direct compromise and bypass of 16) Tor, causing the user to directly connect to an IP of the adversary's 17) choosing.</p></li><li class="listitem"><span class="command"><strong>Correlation of Tor vs Non-Tor Activity</strong></span><p>If direct proxy bypass is not possible, the adversary will likely 18) happily settle for the ability to correlate something a user did via Tor with 19) their non-Tor activity. This can be done with cookies, cache identifiers, 20) javascript events, and even CSS. Sometimes the fact that a user uses Tor may 21) be enough for some authorities.</p></li><li class="listitem"><span class="command"><strong>History disclosure</strong></span><p> 22) The adversary may also be interested in history disclosure: the ability to 23) query a user's history to see if they have issued certain censored search 24) queries, or visited censored sites. 25) </p></li><li class="listitem"><span class="command"><strong>Location information</strong></span><p> 26) 27) Location information such as timezone and locality can be useful for the 28) adversary to determine if a user is in fact originating from one of the 29) regions they are attempting to control, or to zero-in on the geographical 30) location of a particular dissident or whistleblower. 31) 32) </p></li><li class="listitem"><span class="command"><strong>Miscellaneous anonymity set reduction</strong></span><p> 33) 34) Anonymity set reduction is also useful in attempting to zero in on a 35) particular individual. If the dissident or whistleblower is using a rare build 36) of Firefox for an obscure operating system, this can be very useful 37) information for tracking them down, or at least <a class="link" href="#fingerprinting">tracking their activities</a>. 38) 39) </p></li><li class="listitem"><span class="command"><strong>History records and other on-disk 40) information</strong></span><p> 41) In some cases, the adversary may opt for a heavy-handed approach, such as 42) seizing the computers of all Tor users in an area (especially after narrowing 43) the field by the above two pieces of information). History records and cache 44) data are the primary goals here. 45) </p></li></ol></div></div><div class="sect3" title="Adversary Capabilities - Positioning"><div class="titlepage"><div><div><h4 class="title"><a id="adversarypositioning"></a>Adversary Capabilities - Positioning</h4></div></div></div><p> 46) The adversary can position themselves at a number of different locations in 47) order to execute their attacks. 48) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><span class="command"><strong>Exit Node or Upstream Router</strong></span><p> 49) The adversary can run exit nodes, or alternatively, they may control routers 50) upstream of exit nodes. Both of these scenarios have been observed in the 51) wild. 52) </p></li><li class="listitem"><span class="command"><strong>Adservers and/or Malicious Websites</strong></span><p> 53) The adversary can also run websites, or more likely, they can contract out 54) ad space from a number of different adservers and inject content that way. For 55) some users, the adversary may be the adservers themselves. It is not 56) inconceivable that adservers may try to subvert or reduce a user's anonymity 57) through Tor for marketing purposes. 58) </p></li><li class="listitem"><span class="command"><strong>Local Network/ISP/Upstream Router</strong></span><p> 59) The adversary can also inject malicious content at the user's upstream router 60) when they have Tor disabled, in an attempt to correlate their Tor and Non-Tor 61) activity. 62) </p></li><li class="listitem"><span class="command"><strong>Physical Access</strong></span><p> 63) Some users face adversaries with intermittent or constant physical access. 64) Users in Internet cafes, for example, face such a threat. In addition, in 65) countries where simply using tools like Tor is illegal, users may face 66) confiscation of their computer equipment for excessive Tor usage or just 67) general suspicion. 68) </p></li></ol></div></div><div class="sect3" title="Adversary Capabilities - Attacks"><div class="titlepage"><div><div><h4 class="title"><a id="attacks"></a>Adversary Capabilities - Attacks</h4></div></div></div><p> 69) 70) The adversary can perform the following attacks from a number of different 71) positions to accomplish various aspects of their goals. It should be noted 72) that many of these attacks (especially those involving IP address leakage) are 73) often performed by accident by websites that simply have Javascript, dynamic 74) CSS elements, and plugins. Others are performed by adservers seeking to 75) correlate users' activity across different IP addresses, and still others are 76) performed by malicious agents on the Tor network and at national firewalls. 77) 78) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><span class="command"><strong>Inserting Javascript</strong></span><p> 79) If not properly disabled, Javascript event handlers and timers 80) can cause the browser to perform network activity after Tor has been disabled, 81) thus allowing the adversary to correlate Tor and Non-Tor activity and reveal 82) a user's non-Tor IP address. Javascript 83) also allows the adversary to execute <a class="ulink" href="http://whattheinternetknowsaboutyou.com/" target="_top">history disclosure attacks</a>: 84) to query the history via the different attributes of 'visited' links to search 85) for particular google queries, sites, or even to <a class="ulink" href="http://www.mikeonads.com/2008/07/13/using-your-browser-url-history-estimate-gender/" target="_top">profile 86) users based on gender and other classifications</a>. Finally, 87) Javascript can be used to query the user's timezone via the 88) <code class="function">Date()</code> object, and to reduce the anonymity set by querying 89) the <code class="function">navigator</code> object for operating system, CPU, locale, 90) and user agent information. 91) </p></li><li class="listitem"><span class="command"><strong>Inserting Plugins</strong></span><p> 92) 93) Plugins are abysmal at obeying the proxy settings of the browser. Every plugin 94) capable of performing network activity that the author has 95) investigated is also capable of performing network activity independent of 96) browser proxy settings - and often independent of its own proxy settings. 97) Sites that have plugin content don't even have to be malicious to obtain a 98) user's 99) Non-Tor IP (it usually leaks by itself), though <a class="ulink" href="http://decloak.net" target="_top">plenty of active 100) exploits</a> are possible as well. In addition, plugins can be used to store unique identifiers that are more 101) difficult to clear than standard cookies. 102) <a class="ulink" href="http://epic.org/privacy/cookies/flash.html" target="_top">Flash-based 103) cookies</a> fall into this category, but there are likely numerous other 104) examples. 105) 106) </p></li><li class="listitem"><span class="command"><strong>Inserting CSS</strong></span><p> 107) 108) CSS can also be used to correlate Tor and Non-Tor activity and reveal a user's 109) Non-Tor IP address, via the usage of 110) <a class="ulink" href="http://www.tjkdesign.com/articles/css%20pop%20ups/" target="_top">CSS 111) popups</a> - essentially CSS-based event handlers that fetch content via 112) CSS's onmouseover attribute. If these popups are allowed to perform network 113) activity in a different Tor state than they were loaded in, they can easily 114) correlate Tor and Non-Tor activity and reveal a user's IP address. In 115) addition, CSS can also be used without Javascript to perform <a class="ulink" href="http://ha.ckers.org/weird/CSS-history.cgi" target="_top">CSS-only history disclosure 116) attacks</a>. 117) </p></li><li class="listitem"><span class="command"><strong>Read and insert cookies</strong></span><p> 118) 119) An adversary in a position to perform MITM content alteration can inject 120) document content elements to both read and inject cookies for 121) arbitrary domains. In fact, many "SSL secured" websites are vulnerable to this 122) sort of <a class="ulink" href="http://seclists.org/bugtraq/2007/Aug/0070.html" target="_top">active 123) sidejacking</a>. 124) 125) </p></li><li class="listitem"><span class="command"><strong>Create arbitrary cached content</strong></span><p> 126) 127) Likewise, the browser cache can also be used to <a class="ulink" href="http://crypto.stanford.edu/sameorigin/safecachetest.html" target="_top">store unique 128) identifiers</a>. Since by default the cache has no same-origin policy, 129) these identifiers can be read by any domain, making them an ideal target for 130) adserver-class adversaries. 131) 132) </p></li><li class="listitem"><a id="fingerprinting"></a><span class="command"><strong>Fingerprint users based on browser 133) attributes</strong></span><p> 134) 135) There is an absurd amount of information available to websites via attributes 136) of the browser. This information can be used to reduce anonymity set, or even 137) <a class="ulink" href="http://mandark.fr/0x000000/articles/Total_Recall_On_Firefox..html" target="_top">uniquely 138) fingerprint individual users</a>. </p><p> 139) For illustration, let's perform a 140) back-of-the-envelope calculation on the number of anonymity sets for just the 141) resolution information available in the <a class="ulink" href="http://developer.mozilla.org/en/docs/DOM:window" target="_top">window</a> and 142) <a class="ulink" href="http://developer.mozilla.org/en/docs/DOM:window.screen" target="_top">window.screen</a> 143) objects. Browser window resolution information provides something like 144) (1280-640)(1024-480)=348160 different anonymity sets. Desktop resolution 145) information contributes about another factor of 5 (for about 5 resolutions in 146) typical use). In addition, the dimensions and position of the desktop taskbar 147) are available, which can reveal hints on OS information. This boosts the count 148) by a factor of 5 (for each of the major desktop taskbars - Windows, OSX, KDE 149) and Gnome, and None). Subtracting the browser content window 150) size from the browser outer window size provide yet more information. 151) Firefox toolbar presence gives about a factor of 8 (3 toolbars on/off give 152) 2<sup>3</sup>=8). Interface effects such as titlebar fontsize 153) and window manager settings gives a factor of about 9 (say 3 common font sizes 154) for the titlebar and 3 common sizes for browser GUI element fonts). 155) Multiply this all out, and you have (1280-640)(1024-480)5589 ~= 156) 2<sup>29</sup>, or a 29 bit identifier based on resolution 157) information alone. </p><p> 158) 159) Of course, this space is non-uniform and prone to incremental changes. 160) However, if a bit vector space consisting of the above extracted attributes 161) were used instead of the hash approach from <a class="ulink" href="http://mandark.fr/0x000000/articles/Total_Recall_On_Firefox..html" target="_top">The Hacker 162) Webzine article above</a>, minor changes in browser window resolution will 163) no longer generate totally new identifiers. 164) 165) </p><p> 166) 167) To add insult to injury, <a class="ulink" href="http://pseudo-flaw.net/content/tor/torbutton/" target="_top">chrome URL disclosure 168) attacks</a> mean that each and every extension on <a class="ulink" href="https://addons.mozilla.org" target="_top">addons.mozilla.org</a> adds another bit 169) to that 2<sup>29</sup>. With hundreds of popular extensions 170) and thousands of extensions total, it is easy to see that this sort of 171) information is an impressively powerful identifier if used properly by a 172) competent and determined adversary such as an ad network. Again, a 173) nearest-neighbor bit vector space approach here would also gracefully handle 174) incremental changes to installed extensions. 175) 176) </p></li><li class="listitem"><span class="command"><strong>Remotely or locally exploit browser and/or 177) OS</strong></span><p> 178) Last, but definitely not least, the adversary can exploit either general 179) browser vulnerabilities, plugin vulnerabilities, or OS vulnerabilities to 180) install malware and surveillance software. An adversary with physical access 181) can perform similar actions. Regrettably, this last attack capability is 182) outside of Torbutton's ability to defend against, but it is worth mentioning 183) for completeness. 184) </p></li></ol></div></div></div><div class="sect2" title="1.2. Torbutton Requirements"><div class="titlepage"><div><div><h3 class="title"><a id="requirements"></a>1.2. Torbutton Requirements</h3></div></div></div><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3> 185) 186) Since many settings satisfy multiple requirements, this design document is 187) organized primarily by Torbutton components and settings. However, if you are 188) the type that would rather read the document from the requirements 189) perspective, it is in fact possible to search for each of the following 190) requirement phrases in the text to find the relevant features that help meet 191) that requirement. 192) 193) </div><p> 194) 195) From the above Adversary Model, a number of requirements become clear. 196) 197) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a id="proxy"></a><span class="command"><strong>Proxy Obedience</strong></span><p>The browser 198) MUST NOT bypass Tor proxy settings for any content.</p></li><li class="listitem"><a id="isolation"></a><span class="command"><strong>Network Isolation</strong></span><p>Pages MUST NOT perform any network activity in a Tor state different 199) from the state they were originally loaded in.</p></li><li class="listitem"><a id="state"></a><span class="command"><strong>State Separation</strong></span><p>Browser state (cookies, cache, history, 'DOM storage'), accumulated in 200) one Tor state MUST NOT be accessible via the network in 201) another Tor state.</p></li><li class="listitem"><a id="undiscoverability"></a><span class="command"><strong>Tor Undiscoverability</strong></span><p>With 202) the advent of bridge support in Tor 0.2.0.x, there are now a class of Tor 203) users whose network fingerprint does not obviously betray the fact that they 204) are using Tor. This should extend to the browser as well - Torbutton MUST NOT 205) reveal its presence while Tor is disabled.</p></li><li class="listitem"><a id="disk"></a><span class="command"><strong>Disk Avoidance</strong></span><p>The browser SHOULD NOT write any Tor-related state to disk, or store it 206) in memory beyond the duration of one Tor toggle.</p></li><li class="listitem"><a id="location"></a><span class="command"><strong>Location Neutrality</strong></span><p>The browser SHOULD NOT leak location-specific information, such as 207) timezone or locale via Tor.</p></li><li class="listitem"><a id="setpreservation"></a><span class="command"><strong>Anonymity Set 208) Preservation</strong></span><p>The browser SHOULD NOT leak any other anonymity set reducing information 209) (such as user agent, extension presence, and resolution information) 210) automatically via Tor. The assessment of the attacks above should make it clear 211) that anonymity set reduction is a very powerful method of tracking and 212) eventually identifying anonymous users. 213) </p></li><li class="listitem"><a id="updates"></a><span class="command"><strong>Update Safety</strong></span><p>The browser 214) SHOULD NOT perform unauthenticated updates or upgrades via Tor.</p></li><li class="listitem"><a id="interoperate"></a><span class="command"><strong>Interoperability</strong></span><p>Torbutton SHOULD interoperate with third-party proxy switchers that 215) enable the user to switch between a number of different proxies. It MUST 216) provide full Tor protection in the event a third-party proxy switcher has 217) enabled the Tor proxy settings.</p></li></ol></div></div><div class="sect2" title="1.3. Extension Layout"><div class="titlepage"><div><div><h3 class="title"><a id="layout"></a>1.3. Extension Layout</h3></div></div></div><p>Firefox extensions consist of two main categories of code: 'Components' and 218) 'Chrome'. Components are a fancy name for classes that implement a given 219) interface or interfaces. In Firefox, components <a class="ulink" href="https://developer.mozilla.org/en/XPCOM" target="_top">can be 220) written</a> in C++, 221) Javascript, or a mixture of both. Components have two identifiers: their 222) '<a class="ulink" href="http://www.mozilla.org/projects/xpcom/book/cxc/html/quicktour2.html#1005005" target="_top">Contract 223) ID</a>' (a human readable path-like string), and their '<a class="ulink" href="http://www.mozilla.org/projects/xpcom/book/cxc/html/quicktour2.html#1005329" target="_top">Class 224) ID</a>' (a GUID hex-string). In addition, the interfaces they implement each have a hex 225) 'Interface ID'. It is possible to 'hook' system components - to reimplement 226) their interface members with your own wrappers - but only if the rest of the 227) browser refers to the component by its Contract ID. If the browser refers to 228) the component by Class ID, it bypasses your hooks in that use case. 229) Technically, it may be possible to hook Class IDs by unregistering the 230) original component, and then re-registering your own, but this relies on 231) obsolete and deprecated interfaces and has proved to be less than 232) stable.</p><p>'Chrome' is a combination of XML and Javascript used to describe a window. 233) Extensions are allowed to create 'overlays' that are 'bound' to existing XML 234) window definitions, or they can create their own windows. The DTD for this XML
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`235) is called <a class="ulink" href="http://developer.mozilla.org/en/docs/XUL_Reference" target="_top">XUL</a>.</p></div></div><div class="sect1" title="2. Components"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id2976187"></a>2. Components</h2></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`236) 237) Torbutton installs components for two purposes: hooking existing components to 238) reimplement their interfaces; and creating new components that provide 239) services to other pieces of the extension. 240)`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`241) </p><div class="sect2" title="2.1. Hooked Components"><div class="titlepage"><div><div><h3 class="title"><a id="id2969623"></a>2.1. Hooked Components</h3></div></div></div><p>Torbutton makes extensive use of Contract ID hooking, and implements some`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	242) of its own standalone components as well. Let's discuss the hooked components 243) first.</p><div class="sect3" title="@mozilla.org/browser/sessionstore;1 - components/nsSessionStore36.js"><div class="titlepage"><div><div><h4 class="title"><a id="sessionstore"></a><a class="ulink" href="http://developer.mozilla.org/en/docs/nsISessionStore" target="_top">@mozilla.org/browser/sessionstore;1</a> - 244) <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/nsSessionStore36.js" target="_top">components/nsSessionStore36.js</a></h4></div></div></div><p>These components address the <a class="link" href="#disk">Disk Avoidance</a> 245) requirements of Torbutton. As stated in the requirements, Torbutton needs to 246) prevent Tor tabs from being written to disk by the Firefox session store for a 247) number of reasons, primary among them is the fact that Firefox can crash at 248) any time, and a restart can cause you to fetch tabs in the incorrect Tor 249) state.</p><p>These components illustrate a complication with Firefox hooking: you can 250) only hook member functions of a class if they are published in an 251) interface that the class implements. Unfortunately, the sessionstore has no 252) published interface that is amenable to disabling the writing out of Tor tabs 253) in specific. As such, Torbutton had to include the <span class="emphasis"><em>entire</em></span> 254) nsSessionStore from both Firefox 2.0, 3.0, 3.5 and 3.6 255) with a couple of modifications to prevent tabs that were loaded with Tor 256) enabled from being written to disk, and some version detection code to 257) determine which component to load. The <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/nsSessionStore36.diff" target="_top">diff against the original session 258) store</a> is included in the git repository.</p></div><div class="sect3" title="@mozilla.org/uriloader/external-protocol-service;1 , @mozilla.org/uriloader/external-helper-app-service;1, and @mozilla.org/mime;1 - components/external-app-blocker.js"><div class="titlepage"><div><div><h4 class="title"><a id="appblocker"></a><a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/uriloader/external-protocol-service%3B1" target="_top">@mozilla.org/uriloader/external-protocol-service;1 259) </a>, <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/uriloader/external-helper-app-service%3B1" target="_top">@mozilla.org/uriloader/external-helper-app-service;1</a>, 260) and <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/mime%3B1" target="_top">@mozilla.org/mime;1</a> 261) - <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/external-app-blocker.js" target="_top">components/external-app-blocker.js</a></h4></div></div></div><p> 262) Due to <a class="link" href="#FirefoxBugs" title="6. Relevant Firefox Bugs">Firefox Bug</a> <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=440892" target="_top">440892</a> allowing Firefox 3.x to automatically launch some 263) applications without user intervention, Torbutton had to wrap the three 264) components involved in launching external applications to provide user 265) confirmation before doing so while Tor is enabled. Since external applications 266) do not obey proxy settings, they can be manipulated to automatically connect 267) back to arbitrary servers outside of Tor with no user intervention. Fixing 268) this issue helps to satisfy Torbutton's <a class="link" href="#proxy">Proxy 269) Obedience</a> Requirement.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`270) </p></div><div class="sect3" title="@mozilla.org/browser/sessionstartup;1 - components/crash-observer.js"><div class="titlepage"><div><div><h4 class="title"><a id="id2962061"></a><a class="ulink" href="http://lxr.mozilla.org/seamonkey/source/browser/components/sessionstore/src/nsSessionStartup.js" target="_top">@mozilla.org/browser/sessionstartup;1</a> -`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	271) <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/crash-observer.js" target="_top">components/crash-observer.js</a></h4></div></div></div><p>This component wraps the Firefox Session Startup component that is in 272) charge of <a class="ulink" href="http://developer.mozilla.org/en/docs/Session_store_API" target="_top">restoring saved 273) sessions</a>. The wrapper's only job is to intercept the 274) <code class="function">doRestore()</code> function, which is called by Firefox if it is determined that the 275) browser crashed and the session needs to be restored. The wrapper notifies the 276) Torbutton chrome that the browser crashed by setting the pref 277) <span class="command"><strong>extensions.torbutton.crashed</strong></span>, or that it is a normal 278) startup via the pref <span class="command"><strong>extensions.torbutton.noncrashed</strong></span>. The Torbutton Chrome <a class="ulink" href="https://developer.mozilla.org/en/NsIPrefBranch2#addObserver.28.29" target="_top">listens for a 279) preference change</a> for this value and then does the appropriate cleanup. This 280) includes setting the Tor state to the one the user selected for crash recovery 281) in the preferences window (<span class="command"><strong>extensions.torbutton.restore_tor</strong></span>), and 282) restoring cookies for the corresponding cookie jar, if it exists.</p><p>By performing this notification, this component assists in the 283) <a class="link" href="#proxy">Proxy Obedience</a>, and <a class="link" href="#isolation">Network Isolation</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`284) </p></div><div class="sect3" title="@mozilla.org/browser/global-history;2 - components/ignore-history.js"><div class="titlepage"><div><div><h4 class="title"><a id="id2970544"></a><a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/browser/global-history;2" target="_top">@mozilla.org/browser/global-history;2</a>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	285) - <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/ignore-history.js" target="_top">components/ignore-history.js</a></h4></div></div></div><p>This component was contributed by <a class="ulink" href="http://www.collinjackson.com/" target="_top">Collin Jackson</a> as a method for defeating 286) CSS and Javascript-based methods of history disclosure. The global-history 287) component is what is used by Firefox to determine if a link was visited or not 288) (to apply the appropriate style to the link). By hooking the <a class="ulink" href="https://developer.mozilla.org/en/nsIGlobalHistory2#isVisited.28.29" target="_top">isVisited</a> 289) and <a class="ulink" href="https://developer.mozilla.org/en/nsIGlobalHistory2#addURI.28.29" target="_top">addURI</a> 290) methods, Torbutton is able to selectively prevent history items from being 291) added or being displayed as visited, depending on the Tor state and the user's 292) preferences. 293) </p><p> 294) This component helps satisfy the <a class="link" href="#state">State Separation</a> 295) and <a class="link" href="#disk">Disk Avoidance</a> requirements of Torbutton. 296) </p></div><div class="sect3" title="@mozilla.org/browser/livemark-service;2 - components/block-livemarks.js"><div class="titlepage"><div><div><h4 class="title"><a id="livemarks"></a><a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/browser/livemark-service;2" target="_top">@mozilla.org/browser/livemark-service;2</a> 297) - <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/block-livemarks.js" target="_top">components/block-livemarks.js</a></h4></div></div></div><p> 298) 299) The <a class="ulink" href="http://www.mozilla.com/en-US/firefox/livebookmarks.html" target="_top">livemark</a> service 300) is started by a timer that runs 5 seconds after Firefox 301) startup. As a result, we cannot simply call the stopUpdateLivemarks() method to 302) disable it. We must wrap the component to prevent this start() call from 303) firing in the event the browser starts in Tor mode. 304) 305) </p><p> 306) This component helps satisfy the <a class="link" href="#isolation">Network 307) Isolation</a> and <a class="link" href="#setpreservation">Anonymity Set 308) Preservation</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`309) </p></div></div><div class="sect2" title="2.2. New Components"><div class="titlepage"><div><div><h3 class="title"><a id="id2952263"></a>2.2. New Components</h3></div></div></div><p>Torbutton creates four new components that are used throughout the`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`310) extension. These components do not hook any interfaces, nor are they used`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`311) anywhere besides Torbutton itself.</p><div class="sect3" title="@torproject.org/cookie-jar-selector;2 - components/cookie-jar-selector.js"><div class="titlepage"><div><div><h4 class="title"><a id="id2952530"></a><a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cookie-jar-selector.js" target="_top">@torproject.org/cookie-jar-selector;2`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	312) - components/cookie-jar-selector.js</a></h4></div></div></div><p>The cookie jar selector (also based on code from <a class="ulink" href="http://www.collinjackson.com/" target="_top">Collin 313) Jackson</a>) is used by the Torbutton chrome to switch between 314) Tor and Non-Tor cookies. Its operations are simple: sync cookies to disk, then 315) move the current cookies.txt file to the appropriate backup location 316) (cookies-tor.txt or cookies-nontor.txt), and then moving the other cookie jar 317) into place.</p><p> 318) This component helps to address the <a class="link" href="#state">State 319) Isolation</a> requirement of Torbutton.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`320) </p></div><div class="sect3" title="@torproject.org/torbutton-logger;1 - components/torbutton-logger.js"><div class="titlepage"><div><div><h4 class="title"><a id="id2965661"></a><a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/torbutton-logger.js" target="_top">@torproject.org/torbutton-logger;1`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	321) - components/torbutton-logger.js</a></h4></div></div></div><p>The torbutton logger component allows on-the-fly redirection of torbutton 322) logging messages to either Firefox stderr 323) (<span class="command"><strong>extensions.torbutton.logmethod=0</strong></span>), the Javascript error console 324) (<span class="command"><strong>extensions.torbutton.logmethod=1</strong></span>), or the DebugLogger extension (if 325) available - <span class="command"><strong>extensions.torbutton.logmethod=2</strong></span>). It also allows you to 326) change the loglevel on the fly by changing 327) <span class="command"><strong>extensions.torbutton.loglevel</strong></span> (1-5, 1 is most verbose). 328) </p></div><div class="sect3" title="@torproject.org/content-window-mapper;1 - components/window-mapper.js"><div class="titlepage"><div><div><h4 class="title"><a id="windowmapper"></a><a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/window-mapper.js" target="_top">@torproject.org/content-window-mapper;1 329) - components/window-mapper.js</a></h4></div></div></div><p>Torbutton tags Firefox <a class="ulink" href="https://developer.mozilla.org/en/XUL_Tutorial/Tabboxes" target="_top">tabs</a> with a special variable that indicates the Tor 330) state the tab was most recently used under to fetch a page. The problem is 331) that for many Firefox events, it is not possible to determine the tab that is 332) actually receiving the event. The Torbutton window mapper allows the Torbutton 333) chrome and other components to look up a <a class="ulink" href="https://developer.mozilla.org/en/XUL/tabbrowser" target="_top">browser 334) tab</a> for a given <a class="ulink" href="https://developer.mozilla.org/en/nsIDOMWindow" target="_top">HTML content 335) window</a>. It does this by traversing all windows and all browsers, until it 336) finds the browser with the requested <a class="ulink" href="https://developer.mozilla.org/en/XUL/tabbrowser#p-contentWindow" target="_top">contentWindow</a> element. Since the content policy 337) and page loading in general can generate hundreds of these lookups, this 338) result is cached inside the component. 339) </p></div><div class="sect3" title="@torproject.org/cssblocker;1 - components/cssblocker.js"><div class="titlepage"><div><div><h4 class="title"><a id="contentpolicy"></a><a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cssblocker.js" target="_top">@torproject.org/cssblocker;1 340) - components/cssblocker.js</a></h4></div></div></div><p>This is a key component to Torbutton's security measures. When Tor is 341) toggled, Javascript is disabled, and pages are instructed to stop loading. 342) However, CSS is still able to perform network operations by loading styles for 343) onmouseover events and other operations. In addition, favicons can still be 344) loaded by the browser. The cssblocker component prevents this by implementing 345) and registering an <a class="ulink" href="https://developer.mozilla.org/en/nsIContentPolicy" target="_top">nsIContentPolicy</a>. 346) When an nsIContentPolicy is registered, Firefox checks every attempted network 347) request against its <a class="ulink" href="https://developer.mozilla.org/en/nsIContentPolicy#shouldLoad()" target="_top">shouldLoad</a> 348) member function to determine if the load should proceed. In Torbutton's case, 349) the content policy looks up the appropriate browser tab using the <a class="link" href="#windowmapper" title="@torproject.org/content-window-mapper;1 - components/window-mapper.js">window mapper</a>, 350) and checks that tab's load tag against the current Tor state. If the tab was 351) loaded in a different state than the current state, the fetch is denied. 352) Otherwise, it is allowed.</p> This helps to achieve the <a class="link" href="#isolation">Network 353) Isolation</a> requirements of Torbutton. 354) 355) <p>In addition, the content policy also blocks website javascript from 356) <a class="ulink" href="http://pseudo-flaw.net/content/tor/torbutton/" target="_top">querying for 357) versions and existence of extension chrome</a> while Tor is enabled, and 358) also masks the presence of Torbutton to website javascript while Tor is 359) disabled. </p><p> 360) 361) Finally, some of the work that logically belongs to the content policy is 362) instead handled by the <span class="command"><strong>torbutton_http_observer</strong></span> and 363) <span class="command"><strong>torbutton_weblistener</strong></span> in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.js" target="_top">torbutton.js</a>. These two objects handle blocking of 364) Firefox 3 favicon loads, popups, and full page plugins, which for whatever 365) reason are not passed to the Firefox content policy itself (see Firefox Bugs 366) <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=437014" target="_top">437014</a> and 367) <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=401296" target="_top">401296</a>). 368) 369) </p><p> 370) 371) This helps to fulfill both the <a class="link" href="#setpreservation">Anonymity Set Preservation</a> and the <a class="link" href="#undiscoverability">Tor Undiscoverability</a> requirements of
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`372) Torbutton.</p></div></div></div><div class="sect1" title="3. Chrome"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id2962049"></a>3. Chrome</h2></div></div></div><p>The chrome is where all the torbutton graphical elements and windows are`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	373) located. Each window is described as an <a class="ulink" href="http://developer.mozilla.org/en/docs/XUL_Reference" target="_top">XML file</a>, with zero or more Javascript 374) files attached. The scope of these Javascript files is their containing 375) window.</p><div class="sect2" title="3.1. Browser Overlay - torbutton.xul"><div class="titlepage"><div><div><h3 class="title"><a id="browseroverlay"></a>3.1. Browser Overlay - <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.xul" target="_top">torbutton.xul</a></h3></div></div></div><p>The browser overlay, torbutton.xul, defines the toolbar button, the status 376) bar, and events for toggling the button. The overlay code is in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.js" target="_top">chrome/content/torbutton.js</a>. 377) It contains event handlers for preference update, shutdown, upgrade, and 378) location change events.</p><p>The <a class="ulink" href="https://developer.mozilla.org/en/nsIWebProgressListener#onLocationChange" target="_top">location 379) change</a> <a class="ulink" href="https://developer.mozilla.org/en/nsIWebProgress" target="_top">webprogress 380) listener</a>, <span class="command"><strong>torbutton_weblistener</strong></span> is one of the most 381) important parts of the chrome from a security standpoint. It is a <a class="ulink" href="https://developer.mozilla.org/en/nsIWebProgressListener" target="_top">webprogress 382) listener</a> that handles receiving an event every time a page load or 383) iframe load occurs. This class eventually calls down to 384) <code class="function">torbutton_update_tags()</code> and 385) <code class="function">torbutton_hookdoc()</code>, which apply the browser Tor load 386) state tags, plugin permissions, and install the Javascript hooks to hook the 387) <a class="ulink" href="https://developer.mozilla.org/en/DOM/window.screen" target="_top">window.screen</a> 388) object to obfuscate browser and desktop resolution information. 389) 390) </p><p> 391) The browser overlay helps to satisfy a number of Torbutton requirements. These 392) are better enumerated in each of the Torbutton preferences below. However, 393) there are also a number of Firefox preferences set in 394) <code class="function">torbutton_update_status()</code> that aren't governed by any 395) Torbutton setting. These are: 396) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="http://kb.mozillazine.org/Network.security.ports.banned" target="_top">network.security.ports.banned</a><p> 397) Torbutton sets this setting to add ports 8123, 8118, 9050 and 9051 (which it 398) reads from <span class="command"><strong>extensions.torbutton.banned_ports</strong></span>) to the list 399) of ports Firefox is forbidden to access. These ports are Polipo, Privoxy, Tor, 400) and the Tor control port, respectively. This is set for both Tor and Non-Tor 401) usage, and prevents websites from attempting to do http fetches from these 402) ports to see if they are open, which addresses the <a class="link" href="#undiscoverability">Tor Undiscoverability</a> requirement. 403) </p></li><li class="listitem"><a class="ulink" href="http://kb.mozillazine.org/Browser.send_pings" target="_top">browser.send_pings</a><p> 404) This setting is currently always disabled. If anyone ever complains saying 405) that they want their browser to be able to send ping notifications to a 406) page or arbitrary link, I'll make this a pref or Tor-only. But I'm not holding 407) my breath. I haven't checked if the content policy is called for pings, but if 408) not, this setting helps with meeting the <a class="link" href="#isolation">Network 409) Isolation</a> requirement. 410) </p></li><li class="listitem"><a class="ulink" href="http://kb.mozillazine.org/Browser.safebrowsing.remoteLookups" target="_top">browser.safebrowsing.remoteLookups</a><p> 411) Likewise for this setting. I find it hard to imagine anyone who wants to ask 412) Google in real time if each URL they visit is safe, especially when the list 413) of unsafe URLs is downloaded anyway. This helps fulfill the <a class="link" href="#disk">Disk Avoidance</a> requirement, by preventing your entire 414) browsing history from ending up on Google's disks. 415) </p></li><li class="listitem"><a class="ulink" href="http://kb.mozillazine.org/Browser.safebrowsing.enabled" target="_top">browser.safebrowsing.enabled</a><p> 416) Safebrowsing does <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=360387" target="_top">unauthenticated 417) updates under Firefox 2</a>, so it is disabled during Tor usage. 418) This helps fulfill the <a class="link" href="#updates">Update 419) Safety</a> requirement. Firefox 3 has the fix for that bug, and so 420) safebrowsing updates are enabled during Tor usage. 421) </p></li><li class="listitem"><a class="ulink" href="http://kb.mozillazine.org/Network.protocol-handler.warn-external.%28protocol%29" target="_top">network.protocol-handler.warn-external.(protocol)</a><p> 422) If Tor is enabled, we need to prevent random external applications from 423) launching without at least warning the user. This group of settings only 424) partially accomplishes this, however. Applications can still be launched via 425) plugins. The mechanisms for handling this are described under the "Disable 426) Plugins During Tor Usage" preference. This helps fulfill the <a class="link" href="#proxy">Proxy Obedience</a> requirement, by preventing external 427) applications from accessing network resources at the command of Tor-fetched 428) pages. Unfortunately, due to <a class="link" href="#FirefoxBugs" title="6. Relevant Firefox Bugs">Firefox Bug</a> 429) <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=440892" target="_top">440892</a>, 430) these prefs are no longer obeyed. They are set still anyway out of respect for 431) the dead. 432) </p></li><li class="listitem"><a class="ulink" href="http://kb.mozillazine.org/Browser.sessionstore.max_tabs_undo" target="_top">browser.sessionstore.max_tabs_undo</a><p> 433) 434) To help satisfy the Torbutton <a class="link" href="#state">State Separation</a> 435) and <a class="link" href="#isolation">Network Isolation</a> requirements, 436) Torbutton needs to purge the Undo Tab history on toggle to prevent repeat 437) "Undo Close" operations from accidentally restoring tabs from a different Tor 438) State. This purge is accomplished by setting this preference to 0 and then 439) restoring it to the previous user value upon toggle. 440) 441) </p></li><li class="listitem"><span class="command"><strong>security.enable_ssl2</strong></span><p> 442) TLS Session IDs can persist for an indefinite duration, providing an 443) identifier that is sent to TLS sites that can be used to link activity. This 444) is particularly troublesome now that we have certificate verification in place 445) in Firefox 3: The OCSP server can use this Session ID to build a history of 446) TLS sites someone visits, and also correlate their activity as users move from 447) network to network (such as home to work to coffee shop, etc), inside and 448) outside of Tor. To handle this and to help satisfy our <a class="link" href="#state">State Separation Requirement</a>, we currently 449) toggle 450) <span class="command"><strong>security.enable_ssl2</strong></span>, which clears the SSL Session ID 451) cache via the pref observer at <a class="ulink" href="http://mxr.mozilla.org/security/source/security/manager/ssl/src/nsNSSComponent.cpp#2134" target="_top">nsNSSComponent.cpp 452) line 2134</a>. This is an arcane and potentially fragile fix. It would be 453) better if there were a more standard interface for accomplishing the same 454) thing. <a class="link" href="#FirefoxBugs" title="6. Relevant Firefox Bugs">Firefox Bug</a> <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=448747" target="_top">448747</a> has 455) been filed for this. 456) 457) </p></li><li class="listitem"><span class="command"><strong><a class="ulink" href="http://www.mozilla.com/en-US/firefox/geolocation/" target="_top">geo.enabled</a></strong></span><p> 458) 459) Torbutton disables Geolocation support in Firefox 3.5 and above whenever tor 460) is enabled. This helps Torbutton maintain its 461) <a class="link" href="#location">Location Neutrality</a> requirement. 462) While Firefox does prompt before divulging geolocational information, 463) the assumption is that Tor users will never want to give their 464) location away during Tor usage, and even allowing websites to prompt 465) them to do so will only cause confusion and accidents to happen. Moreover, 466) just because users may approve a site to know their location in non-Tor mode 467) does not mean they want it divulged during Tor mode. 468) 469) </p></li><li class="listitem"><span class="command"><strong><a class="ulink" href="http://kb.mozillazine.org/Browser.zoom.siteSpecific" target="_top">browser.zoom.siteSpecific</a></strong></span><p> 470) 471) Firefox actually remembers your zoom settings for certain sites. CSS 472) and Javascript rule can use this to recognize previous visitors to a site. 473) This helps Torbutton fulfill its <a class="link" href="#state">State Separation</a> 474) requirement. 475) 476) </p></li><li class="listitem"><span class="command"><strong><a class="ulink" href="https://developer.mozilla.org/en/controlling_dns_prefetching" target="_top">network.dns.disablePrefetch</a></strong></span><p> 477) 478) Firefox 3.5 and above implement prefetching of DNS resolution for hostnames in 479) links on a page to decrease page load latency. While Firefox does typically 480) disable this behavior when proxies are enabled, we set this pref for added 481) safety during Tor usage. Additionally, to prevent Tor-loaded tabs from having 482) their links prefetched after a toggle to Non-Tor mode occurs, 483) we also set the docShell attribute 484) <a class="ulink" href="http://www.oxymoronical.com/experiments/apidocs/interface/nsIDocShell" target="_top"> 485) allowDNSPrefetch</a> to false on Tor loaded tabs. This happens in the same 486) positions in the code as those for disabling plugins via the allowPlugins 487) docShell attribute. This helps Torbutton fulfill its <a class="link" href="#isolation">Network Isolation</a> requirement. 488) 489) </p></li><li class="listitem"><span class="command"><strong><a class="ulink" href="http://kb.mozillazine.org/Browser.cache.offline.enable" target="_top">browser.cache.offline.enable</a></strong></span><p> 490) 491) Firefox has the ability to store web applications in a special cache to allow 492) them to continue to operate while the user is offline. Since this subsystem 493) is actually different than the normal disk cache, it must be dealt with 494) separately. Thus, Torbutton sets this preference to false whenever Tor is 495) enabled. This helps Torbutton fulfill its <a class="link" href="#disk">Disk 496) Avoidance</a> and <a class="link" href="#state">State Separation</a> 497) requirements. 498)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	499) </p></li></ol></div></div><div class="sect2" title="3.2. Preferences Window - preferences.xul"><div class="titlepage"><div><div><h3 class="title"><a id="id2941767"></a>3.2. Preferences Window - <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/preferences.xul" target="_top">preferences.xul</a></h3></div></div></div><p>The preferences window of course lays out the Torbutton preferences, with 500) handlers located in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/preferences.js" target="_top">chrome/content/preferences.js</a>.</p></div><div class="sect2" title="3.3. Other Windows"><div class="titlepage"><div><div><h3 class="title"><a id="id2976170"></a>3.3. Other Windows</h3></div></div></div><p>There are additional windows that describe popups for right clicking on 501) the status bar, the toolbutton, and the about page.</p></div></div><div class="sect1" title="4. Toggle Code Path"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id2977751"></a>4. Toggle Code Path</h2></div></div></div><p>
add torbutton design dir fr... Andrew Lewman authored 14 years ago	502) 503) The act of toggling is connected to <code class="function">torbutton_toggle()</code> 504) via the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.xul" target="_top">torbutton.xul</a> 505) and <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/popup.xul" target="_top">popup.xul</a> 506) overlay files. Most of the work in the toggling process is present in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.js" target="_top">torbutton.js</a> 507) 508) </p><p> 509) 510) Toggling is a 3 stage process: Button Click, Proxy Update, and 511) Settings Update. These stages are reflected in the prefs 512) <span class="command"><strong>extensions.torbutton.tor_enabled</strong></span>, 513) <span class="command"><strong>extensions.torbutton.proxies_applied</strong></span>, and 514) <span class="command"><strong>extensions.torbutton.settings_applied</strong></span>. The reason for the 515) three stage preference update is to ensure immediate enforcement of <a class="link" href="#isolation">Network Isolation</a> via the <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">content policy</a>. Since the content window 516) javascript runs on a different thread than the chrome javascript, it is 517) important to properly convey the stages to the content policy to avoid race 518) conditions and leakage, especially with <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=409737" target="_top">Firefox Bug 519) 409737</a> unfixed. The content policy does not allow any network activity 520) whatsoever during this three stage transition. 521)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`522) </p><div class="sect2" title="4.1. Button Click"><div class="titlepage"><div><div><h3 class="title"><a id="id2944154"></a>4.1. Button Click</h3></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	523) 524) This is the first step in the toggling process. When the user clicks the 525) toggle button or the toolbar, <code class="function">torbutton_toggle()</code> is 526) called. This function checks the current Tor status by comparing the current 527) proxy settings to the selected Tor settings, and then sets the proxy settings 528) to the opposite state, and sets the pref 529) <span class="command"><strong>extensions.torbutton.tor_enabled</strong></span> to reflect the new state. 530) It is this proxy pref update that gives notification via the <a class="ulink" href="https://developer.mozilla.org/en/NsIPrefBranch2#addObserver.28.29" target="_top">pref 531) observer</a> 532) <span class="command"><strong>torbutton_unique_pref_observer</strong></span> to perform the rest of the 533) toggle. 534)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`535) </p></div><div class="sect2" title="4.2. Proxy Update"><div class="titlepage"><div><div><h3 class="title"><a id="id2978704"></a>4.2. Proxy Update</h3></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	536) 537) When Torbutton receives any proxy change notifications via its 538) <span class="command"><strong>torbutton_unique_pref_observer</strong></span>, it calls 539) <code class="function">torbutton_set_status()</code> which checks against the Tor 540) settings to see if the Tor proxy settings match the current settings. If so, 541) it calls <code class="function">torbutton_update_status()</code>, which determines if 542) the Tor state has actually changed, and sets 543) <span class="command"><strong>extensions.torbutton.proxies_applied</strong></span> to the appropriate Tor 544) state value, and ensures that 545) <span class="command"><strong>extensions.torbutton.tor_enabled</strong></span> is also set to the correct 546) value. This is decoupled from the button click functionalty via the pref 547) observer so that other addons (such as SwitchProxy) can switch the proxy 548) settings between multiple proxies. 549)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`550) </p></div><div class="sect2" title="4.3. Settings Update"><div class="titlepage"><div><div><h3 class="title"><a id="id2945348"></a>4.3. Settings Update</h3></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	551) 552) The next stage is also handled by 553) <code class="function">torbutton_update_status()</code>. This function sets scores of 554) Firefox preferences, saving the original values to prefs under 555) <span class="command"><strong>extensions.torbutton.saved.*</strong></span>, and performs the history 556) clearing, cookie jaring, and ssl certificate jaring work of Torbutton. At the 557) end of its work, it sets 558) <span class="command"><strong>extensions.torbutton.settings_applied</strong></span>, which signifies the 559) completion of the toggle operation to the <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">content policy</a>. 560)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`561) </p></div></div><div class="sect1" title="5. Description of Options"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id2966553"></a>5. Description of Options</h2></div></div></div><p>This section provides a detailed description of Torbutton's options. Each`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`562) option is presented as the string from the preferences window, a summary, the 563) preferences it touches, and the effect this has on the components, chrome, and`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`564) browser properties.</p><div class="sect2" title="5.1. Test Settings"><div class="titlepage"><div><div><h3 class="title"><a id="id2948284"></a>5.1. Test Settings</h3></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	565) This button under the Proxy Settings tab provides a way to verify that the 566) proxy settings are correct, and actually do route through the Tor network. It 567) performs this check by issuing an <a class="ulink" href="http://developer.mozilla.org/en/docs/XMLHttpRequest" target="_top">XMLHTTPRequest</a> 568) for <a class="ulink" href="https://check.torproject.org/?TorButton=True" target="_top">https://check.torproject.org/?Torbutton=True</a>. 569) This is a special page that returns very simple, yet well-formed XHTML that 570) Torbutton can easily inspect for a hidden link with an id of 571) <span class="command"><strong>TorCheckResult</strong></span> and a target of <span class="command"><strong>success</strong></span> 572) or <span class="command"><strong>failure</strong></span> to indicate if the 573) user hit the page from a Tor IP, a non-Tor IP. This check is handled in 574) <code class="function">torbutton_test_settings()</code> in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.js" target="_top">torbutton.js</a>. 575) Presenting the results to the user is handled by the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/preferences.xul" target="_top">preferences 576) window</a> 577) callback <code class="function">torbutton_prefs_test_settings()</code> in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/preferences.js" target="_top">preferences.js</a>. 578) 579) </p></div><div class="sect2" title="5.2. Disable plugins on Tor Usage (crucial)"><div class="titlepage"><div><div><h3 class="title"><a id="plugins"></a>5.2. Disable plugins on Tor Usage (crucial)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.no_tor_plugins</strong></span></p><p>Java and plugins <a class="ulink" href="http://java.sun.com/j2se/1.5.0/docs/api/java/net/class-use/NetworkInterface.html" target="_top">can query</a> the <a class="ulink" href="http://www.rgagnon.com/javadetails/java-0095.html" target="_top">local IP 580) address</a> and report it back to the 581) remote site. They can also <a class="ulink" href="http://decloak.net" target="_top">bypass proxy settings</a> and directly connect to a 582) remote site without Tor. Every browser plugin we have tested with Firefox has 583) some form of network capability, and every one ignores proxy settings or worse - only 584) partially obeys them. This includes but is not limited to: 585) QuickTime, Windows Media Player, RealPlayer, mplayerplug-in, AcroRead, and 586) Flash. 587) 588) </p><p> 589) Enabling this preference causes the above mentioned Torbutton chrome web progress 590) listener <span class="command"><strong>torbutton_weblistener</strong></span> to disable Java via <span class="command"><strong>security.enable_java</strong></span> and to disable 591) plugins via the browser <a class="ulink" href="https://developer.mozilla.org/en/XUL%3aProperty%3adocShell" target="_top">docShell</a> 592) attribute <span class="command"><strong>allowPlugins</strong></span>. These flags are set every time a new window is 593) created (<code class="function">torbutton_tag_new_browser()</code>), every time a web 594) load 595) event occurs 596) (<code class="function">torbutton_update_tags()</code>), and every time the tor state is changed 597) (<code class="function">torbutton_update_status()</code>). As a backup measure, plugins are also 598) prevented from loading by the content policy in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cssblocker.js" target="_top">@torproject.org/cssblocker;1</a> if Tor is 599) enabled and this option is set. 600) </p><p>All of this turns out to be insufficient if the user directly clicks 601) on a plugin-handled mime-type. <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=401296" target="_top">In this case</a>, 602) the browser decides that maybe it should ignore all these other settings and 603) load the plugin anyways, because maybe the user really did want to load it 604) (never mind this same load-style could happen automatically with meta-refresh 605) or any number of other ways..). To handle these cases, Torbutton stores a list 606) of plugin-handled mime-types, and sets the pref 607) <span class="command"><strong>plugin.disable_full_page_plugin_for_types</strong></span> to this list. 608) Additionally, (since nothing can be assumed when relying on Firefox 609) preferences and internals) if it detects a load of one of them from the web 610) progress listener, it cancels the request, tells the associated DOMWindow to 611) stop loading, clears the document, AND throws an exception. Anything short of 612) all this and the plugin managed to find some way to load. 613) </p><p> 614) All this could be avoided, of course, if Firefox would either <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=401296" target="_top">obey 615) allowPlugins</a> for directly visited URLs, or notify its content policy for such 616) loads either <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=309524" target="_top">via</a> <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=380556" target="_top">shouldProcess</a> or shouldLoad. The fact that it does not is 617) not very encouraging. 618) </p><p> 619) 620) Since most plugins completely ignore browser proxy settings, the actions 621) performed by this setting are crucial to satisfying the <a class="link" href="#proxy">Proxy Obedience</a> requirement. 622)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	623) </p></div><div class="sect2" title="5.3. Isolate Dynamic Content to Tor State (crucial)"><div class="titlepage"><div><div><h3 class="title"><a id="id2965289"></a>5.3. Isolate Dynamic Content to Tor State (crucial)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.isolate_content</strong></span></p><p>Enabling this preference is what enables the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cssblocker.js" target="_top">@torproject.org/cssblocker;1</a> content policy
add torbutton design dir fr... Andrew Lewman authored 14 years ago	624) mentioned above, and causes it to block content load attempts in pages an 625) opposite Tor state from the current state. Freshly loaded <a class="ulink" href="https://developer.mozilla.org/en/XUL/tabbrowser" target="_top">browser 626) tabs</a> are tagged 627) with a <span class="command"><strong>__tb_load_state</strong></span> member in 628) <code class="function">torbutton_update_tags()</code> and this 629) value is compared against the current tor state in the content policy.</p><p>It also kills all Javascript in each page loaded under that state by 630) toggling the <span class="command"><strong>allowJavascript</strong></span> <a class="ulink" href="https://developer.mozilla.org/en/XUL%3aProperty%3adocShell" target="_top">docShell</a> property, and issues a 631) <a class="ulink" href="https://developer.mozilla.org/en/XPCOM_Interface_Reference/nsIWebNavigation#stop()" target="_top">webNavigation.stop(webNavigation.STOP_ALL)</a> to each browser tab (the 632) equivalent of hitting the STOP button).</p><p> 633) 634) Unfortunately, <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=409737" target="_top">Firefox bug 635) 409737</a> prevents <span class="command"><strong>docShell.allowJavascript</strong></span> from killing 636) all event handlers, and event handlers registered with <a class="ulink" href="http://developer.mozilla.org/en/docs/DOM:element.addEventListener" target="_top">addEventListener()</a> 637) are still able to execute. The <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">Torbutton Content 638) Policy</a> should prevent such code from performing network activity within 639) the current tab, but activity that happens via a popup window or via a 640) Javascript redirect can still slip by. For this reason, Torbutton blocks 641) popups by checking for a valid <a class="ulink" href="http://developer.mozilla.org/en/docs/DOM:window.opener" target="_top">window.opener</a> 642) attribute in <code class="function">torbutton_check_progress()</code>. If the window 643) has an opener from a different Tor state, its load is blocked. The content 644) policy also takes similar action to prevent Javascript redirects. This also 645) has the side effect/feature of preventing the user from following any links 646) from a page loaded in an opposite Tor state. 647) 648) </p><p> 649) This setting is responsible for satisfying the <a class="link" href="#isolation">Network Isolation</a> requirement. 650) </p></div><div class="sect2" title="5.4. Hook Dangerous Javascript"><div class="titlepage"><div><div><h3 class="title"><a id="jshooks"></a>5.4. Hook Dangerous Javascript</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.kill_bad_js</strong></span></p><p>This setting enables injection of the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/jshooks.js" target="_top">Javascript 651) hooking code</a>. This is done in the chrome in 652) <code class="function">torbutton_hookdoc()</code>, which is called ultimately by both the 653) <a class="ulink" href="https://developer.mozilla.org/en/nsIWebProgressListener" target="_top">webprogress 654) listener</a> <span class="command"><strong>torbutton_weblistener</strong></span> and the <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">content policy</a> (the latter being a hack to handle 655) javascript: urls). 656) 657) In the Firefox 2 days, this option did a lot more than 658) it does now. It used to be responsible for timezone and improved useragent 659) spoofing, and history object cloaking. However, now it only provides 660) obfuscation of the <a class="ulink" href="https://developer.mozilla.org/en/DOM/window.screen" target="_top">window.screen</a> 661) object to mask your browser and desktop resolution. 662) The resolution hooks 663) effectively make the Firefox browser window appear to websites as if the renderable area 664) takes up the entire desktop, has no toolbar or other GUI element space, and 665) the desktop itself has no toolbars. 666) These hooks drastically reduce the amount of information available to do <a class="link" href="#fingerprinting">anonymity set reduction attacks</a> and help to 667) meet the <a class="link" href="#setpreservation">Anonymity Set Preservation</a> 668) requirements. Unfortunately, Gregory Fleischer discovered it is still possible 669) to retrieve the original screen values by using <a class="ulink" href="http://pseudo-flaw.net/tor/torbutton/unmask-sandbox-xpcnativewrapper.html" target="_top">XPCNativeWrapper</a> 670) or <a class="ulink" href="http://pseudo-flaw.net/tor/torbutton/unmask-components-lookupmethod.html" target="_top">Components.lookupMethod</a>.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`671) We are still looking for a workaround as of Torbutton 1.2.5.`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`672) 673) 674)`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`675) </p></div><div class="sect2" title="5.5. Resize windows to multiples of 50px during Tor usage (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2964952"></a>5.5. Resize windows to multiples of 50px during Tor usage (recommended)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.resize_windows</strong></span></p><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	676) 677) This option drastically cuts down on the number of distinct anonymity sets 678) that divide the Tor web userbase. Without this setting, the dimensions for a 679) typical browser window range from 600-1200 horizontal pixels and 400-1000 680) vertical pixels, or about 600x600 = 360000 different sets. Resizing the 681) browser window to multiples of 50 on each side reduces the number of sets by 682) 50^2, bringing the total number of sets to 144. Of course, the distribution 683) among these sets are not uniform, but scaling by 50 will improve the situation 684) due to this non-uniformity for users in the less common resolutions. 685) Obviously the ideal situation would be to lie entirely about the browser 686) window size, but this will likely cause all sorts of rendering issues, and is 687) also not implementable in a foolproof way from extension land. 688) 689) </p><p> 690) 691) The implementation of this setting is spread across a couple of different 692) locations in the Torbutton javascript <a class="link" href="#browseroverlay" title="3.1. Browser Overlay - torbutton.xul">browser 693) overlay</a>. Since resizing minimized windows causes them to be restored, 694) and since maximized windows remember their previous size to the pixel, windows 695) must be resized before every document load (at the time of browser tagging) 696) via <code class="function">torbutton_check_round()</code>, called by 697) <code class="function">torbutton_update_tags()</code>. To prevent drift, the extension 698) tracks the original values of the windows and uses this to perform the 699) rounding on document load. In addition, to prevent the user from resizing a 700) window to a non-50px multiple, a resize listener 701) (<code class="function">torbutton_do_resize()</code>) is installed on every new browser 702) window to record the new size and round it to a 50px multiple while Tor is 703) enabled. In all cases, the browser's contentWindow.innerWidth and innerHeight 704) are set. This ensures that there is no discrepancy between the 50 pixel cutoff 705) and the actual renderable area of the browser (so that it is not possible to 706) infer toolbar size/presence by the distance to the nearest 50 pixel roundoff). 707) 708) </p><p> 709) This setting helps to meet the <a class="link" href="#setpreservation">Anonymity Set Preservation</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`710) </p></div><div class="sect2" title="5.6. Disable Updates During Tor"><div class="titlepage"><div><div><h3 class="title"><a id="id2977086"></a>5.6. Disable Updates During Tor</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.no_updates</strong></span></p><p>This setting causes Torbutton to disable the four <a class="ulink" href="http://wiki.mozilla.org/Update:Users/Checking_For_Updates#Preference_Controls_and_State" target="_top">Firefox`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	711) update settings</a> during Tor 712) usage: <span class="command"><strong>extensions.update.enabled</strong></span>, 713) <span class="command"><strong>app.update.enabled</strong></span>, 714) <span class="command"><strong>app.update.auto</strong></span>, and 715) <span class="command"><strong>browser.search.update</strong></span>. These prevent the 716) browser from updating extensions, checking for Firefox upgrades, and 717) checking for search plugin updates while Tor is enabled. 718) </p><p> 719) This setting satisfies the <a class="link" href="#updates">Update Safety</a> requirement.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	720) </p></div><div class="sect2" title="5.7. Redirect Torbutton Updates Via Tor (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937206"></a>5.7. Redirect Torbutton Updates Via Tor (recommended)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.update_torbutton_via_tor</strong></span></p><p>This setting causes Torbutton to install an 721) 722) <a class="ulink" href="https://developer.mozilla.org/en/nsIProtocolProxyFilter" target="_top">nsIProtocolProxyFilter</a> 723) in order to redirect all version update checks and Torbutton update downloads 724) via Tor, regardless of if Tor is enabled or not. This was done both to address 725) concerns about data retention done by <a class="ulink" href="https://www.addons.mozilla.org" target="_top">addons.mozilla.org</a>, as well as to 726) help censored users meet the <a class="link" href="#undiscoverability">Tor 727) Undiscoverability</a> requirement. 728) 729) </p></div><div class="sect2" title="5.8. Disable Search Suggestions during Tor (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937250"></a>5.8. Disable Search Suggestions during Tor (recommended)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.no_search</strong></span></p><p>
add torbutton design dir fr... Andrew Lewman authored 14 years ago	730) This setting causes Torbutton to disable <a class="ulink" href="http://kb.mozillazine.org/Browser.search.suggest.enabled" target="_top"><span class="command"><strong>browser.search.suggest.enabled</strong></span></a> 731) during Tor usage. 732) This governs if you get Google search suggestions during Tor 733) usage. Your Google cookie is transmitted with google search suggestions, hence 734) this is recommended to be disabled. 735) 736) </p><p> 737) While this setting doesn't satisfy any Torbutton requirements, the fact that 738) cookies are transmitted for partially typed queries does not seem desirable 739) for Tor usage.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`740) </p></div><div class="sect2" title="5.9. Disable livemarks updates during Tor usage (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937289"></a>5.9. Disable livemarks updates during Tor usage (recommended)</h3></div></div></div><p>Option:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	741) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.disable_livemarks</strong></span></td></tr></table><p> 742) </p><p> 743) This option causes Torbutton to prevent Firefox from loading <a class="ulink" href="http://www.mozilla.com/firefox/livebookmarks.html" target="_top">Livemarks</a> during 744) Tor usage. Because people often have very personalized Livemarks (such as RSS 745) feeds of Wikipedia articles they maintain, etc). This is accomplished both by 746) <a class="link" href="#livemarks" title="@mozilla.org/browser/livemark-service;2 - components/block-livemarks.js">wrapping the livemark-service component</a> and 747) by calling stopUpdateLivemarks() on the <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/browser/livemark-service;2" target="_top">Livemark 748) service</a> when Tor is enabled. 749) 750) </p><p> 751) This helps satisfy the <a class="link" href="#isolation">Network 752) Isolation</a> and <a class="link" href="#setpreservation">Anonymity Set 753) Preservation</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`754) </p></div><div class="sect2" title="5.10. Block Tor/Non-Tor access to network from file:// urls (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937361"></a>5.10. Block Tor/Non-Tor access to network from file:// urls (recommended)</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	755) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.block_tor_file_net</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.block_nontor_file_net</strong></span></td></tr></table><p> 756) </p><p> 757) 758) These settings prevent file urls from performing network operations during the 759) respective Tor states. Firefox 2's implementation of same origin policy allows 760) file urls to read and <a class="ulink" href="http://www.gnucitizen.org/blog/content-disposition-hacking/" target="_top">submit 761) arbitrary files from the local filesystem</a> to arbitrary websites. To 762) make matters worse, the 'Content-Disposition' header can be injected 763) arbitrarily by exit nodes to trick users into running arbitrary html files in 764) the local context. These preferences cause the <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">content policy</a> to block access to any network 765) resources from File urls during the appropriate Tor state. 766) 767) </p><p> 768) 769) This preference helps to ensure Tor's <a class="link" href="#isolation">Network 770) Isolation</a> requirement, by preventing file urls from executing network 771) operations in opposite Tor states. Also, allowing pages to submit arbitrary 772) files to arbitrary sites just generally seems like a bad idea. 773)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`774) </p></div><div class="sect2" title="5.11. Close all Tor/Non-Tor tabs and windows on toggle (optional)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937433"></a>5.11. Close all Tor/Non-Tor tabs and windows on toggle (optional)</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	775) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.close_nontor</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.close_tor</strong></span></td></tr></table><p> 776) </p><p> 777) 778) These settings cause Torbutton to enumerate through all windows and close all 779) tabs in each window for the appropriate Tor state. This code can be found in 780) <code class="function">torbutton_update_status()</code>. The main reason these settings 781) exist is as a backup mechanism in the event of any Javascript or content policy 782) leaks due to <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=409737" target="_top">Firefox Bug 783) 409737</a>. Torbutton currently tries to block all Javascript network 784) activity via the content policy, but until that bug is fixed, there is some 785) risk that there are alternate ways to bypass the policy. This option is 786) available as an extra assurance of <a class="link" href="#isolation">Network 787) Isolation</a> for those who would like to be sure that when Tor is toggled 788) all page activity has ceased. It also serves as a potential future workaround 789) in the event a content policy failure is discovered, and provides an additional 790) level of protection for the <a class="link" href="#disk">Disk Avoidance</a> 791) protection so that browser state is not sitting around waiting to be swapped 792) out longer than necessary. 793) 794) </p><p> 795) While this setting doesn't satisfy any Torbutton requirements, the fact that 796) cookies are transmitted for partially typed queries does not seem desirable 797) for Tor usage.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`798) </p></div><div class="sect2" title="5.12. Isolate Access to History navigation to Tor state (crucial)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937514"></a>5.12. Isolate Access to History navigation to Tor state (crucial)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.block_js_history</strong></span></p><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	799) This setting determines if Torbutton installs an <a class="ulink" href="http://www.oxymoronical.com/experiments/apidocs/interface/nsISHistoryListener" target="_top">nsISHistoryListener</a> 800) attached to the <a class="ulink" href="http://www.oxymoronical.com/experiments/apidocs/interface/nsISHistory" target="_top">sessionHistory</a> of 801) of each browser's <a class="ulink" href="https://developer.mozilla.org/en/XUL%3aProperty%3awebNavigation" target="_top">webNavigatator</a>. 802) The nsIShistoryListener is instantiated with a reference to the containing 803) browser window and blocks the back, forward, and reload buttons on the browser 804) navigation bar when Tor is in an opposite state than the one to load the 805) current tab. In addition, Tor clears the session history during a new document 806) load if this setting is enabled. 807) 808) </p><p> 809) 810) This is marked as a crucial setting in part 811) because Javascript access to the history object is indistinguishable from 812) user clicks, and because 813) <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=409737" target="_top">Firefox Bug 814) 409737</a> allows javascript to execute in opposite Tor states, javascript 815) can issue reloads after Tor toggle to reveal your original IP. Even without 816) this bug, however, Javascript is still able to access previous pages in your 817) session history that may have been loaded under a different Tor state, to 818) attempt to correlate your activity. 819) 820) </p><p> 821) 822) This setting helps to fulfill Torbutton's <a class="link" href="#state">State 823) Separation</a> and (until Bug 409737 is fixed) <a class="link" href="#isolation">Network Isolation</a> 824) requirements. 825)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`826) </p></div><div class="sect2" title="5.13. History Access Settings"><div class="titlepage"><div><div><h3 class="title"><a id="id2937598"></a>5.13. History Access Settings</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	827) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.block_thread</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.block_nthread</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.block_thwrite</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.block_nthwrite</strong></span></td></tr></table><p> 828) </p><p>These four settings govern the behavior of the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/ignore-history.js" target="_top">components/ignore-history.js</a> 829) history blocker component mentioned above. By hooking the browser's view of 830) the history itself via the <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/browser/global-history;2" target="_top">@mozilla.org/browser/global-history;2</a> 831) and <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/browser/nav-history-service;1" target="_top">@mozilla.org/browser/nav-history-service;1</a> 832) components, this mechanism defeats all document-based <a class="ulink" href="http://whattheinternetknowsaboutyou.com/" target="_top">history disclosure 833) attacks</a>, including <a class="ulink" href="http://ha.ckers.org/weird/CSS-history.cgi" target="_top">CSS-only attacks</a>. 834) 835) The component also hooks functions involved in writing history to disk via 836) both the <a class="ulink" href="http://developer.mozilla.org/en/docs/Places_migration_guide#History" target="_top">Places 837) Database</a> and the older Firefox 2 mechanisms. 838) 839) </p><p> 840) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> and <a class="link" href="#disk">Disk Avoidance</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`841) </p></div><div class="sect2" title="5.14. Clear History During Tor Toggle (optional)"><div class="titlepage"><div><div><h3 class="title"><a id="id2937711"></a>5.14. Clear History During Tor Toggle (optional)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.clear_history</strong></span></p><p>This setting governs if Torbutton calls`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`842) <a class="ulink" href="https://developer.mozilla.org/en/nsIBrowserHistory#removeAllPages.28.29" target="_top">nsIBrowserHistory.removeAllPages</a> 843) and <a class="ulink" href="http://www.oxymoronical.com/experiments/apidocs/interface/nsISHistory" target="_top">nsISHistory.PurgeHistory</a> 844) for each tab on Tor toggle.</p><p> 845) This setting is an optional way to help satisfy the <a class="link" href="#state">State Separation</a> requirement.`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`846) </p></div><div class="sect2" title="5.15. Block Password+Form saving during Tor/Non-Tor"><div class="titlepage"><div><div><h3 class="title"><a id="id2979251"></a>5.15. Block Password+Form saving during Tor/Non-Tor</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	847) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.block_tforms</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.block_ntforms</strong></span></td></tr></table><p> 848) </p><p>These settings govern if Torbutton disables 849) <span class="command"><strong>browser.formfill.enable</strong></span> 850) and <span class="command"><strong>signon.rememberSignons</strong></span> during Tor and Non-Tor usage. 851) Since form fields can be read at any time by Javascript, this setting is a lot 852) more important than it seems. 853) </p><p> 854) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> and <a class="link" href="#disk">Disk Avoidance</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`855) </p></div><div class="sect2" title="5.16. Block Tor disk cache and clear all cache on Tor Toggle"><div class="titlepage"><div><div><h3 class="title"><a id="id2979312"></a>5.16. Block Tor disk cache and clear all cache on Tor Toggle</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.clear_cache</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	856) </p><p>This option causes Torbutton to call <a class="ulink" href="https://developer.mozilla.org/en/nsICacheService#evictEntries.28.29" target="_top">nsICacheService.evictEntries(0)</a> 857) on Tor toggle to remove all entries from the cache. In addition, this setting 858) causes Torbutton to set <a class="ulink" href="http://kb.mozillazine.org/Browser.cache.disk.enable" target="_top">browser.cache.disk.enable</a> to false. 859) </p><p> 860) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> and <a class="link" href="#disk">Disk Avoidance</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`861) </p></div><div class="sect2" title="5.17. Block disk and memory cache during Tor"><div class="titlepage"><div><div><h3 class="title"><a id="id2979362"></a>5.17. Block disk and memory cache during Tor</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.block_cache</strong></span></p><p>This setting`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	862) causes Torbutton to set <a class="ulink" href="http://kb.mozillazine.org/Browser.cache.memory.enable" target="_top">browser.cache.memory.enable</a>, 863) <a class="ulink" href="http://kb.mozillazine.org/Browser.cache.disk.enable" target="_top">browser.cache.disk.enable</a> and 864) <a class="ulink" href="http://kb.mozillazine.org/Network.http.use-cache" target="_top">network.http.use-cache</a> to false during tor usage. 865) </p><p> 866) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> and <a class="link" href="#disk">Disk Avoidance</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`867) </p></div><div class="sect2" title="5.18. Clear Cookies on Tor Toggle"><div class="titlepage"><div><div><h3 class="title"><a id="id2979414"></a>5.18. Clear Cookies on Tor Toggle</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.clear_cookies</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	868) </p><p> 869) 870) This setting causes Torbutton to call <a class="ulink" href="https://developer.mozilla.org/en/nsICookieManager#removeAll.28.29" target="_top">nsICookieManager.removeAll()</a> on 871) every Tor toggle. In addition, this sets <a class="ulink" href="http://kb.mozillazine.org/Network.cookie.lifetimePolicy" target="_top">network.cookie.lifetimePolicy</a> 872) to 2 for Tor usage, which causes all cookies to be demoted to session cookies, 873) which prevents them from being written to disk. 874) 875) </p><p> 876) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> and <a class="link" href="#disk">Disk Avoidance</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`877) </p></div><div class="sect2" title="5.19. Store Non-Tor cookies in a protected jar"><div class="titlepage"><div><div><h3 class="title"><a id="id2979465"></a>5.19. Store Non-Tor cookies in a protected jar</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.cookie_jars</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	878) </p><p> 879) 880) This setting causes Torbutton to use <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cookie-jar-selector.js" target="_top">@torproject.org/cookie-jar-selector;2</a> to store 881) non-tor cookies in a cookie jar during Tor usage, and clear the Tor cookies 882) before restoring the jar. 883) </p><p> 884) This setting also sets <a class="ulink" href="http://kb.mozillazine.org/Network.cookie.lifetimePolicy" target="_top">network.cookie.lifetimePolicy</a> 885) to 2 for Tor usage, which causes all cookies to be demoted to session cookies, 886) which prevents them from being written to disk. 887) 888) </p><p> 889) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> and <a class="link" href="#disk">Disk Avoidance</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`890) </p></div><div class="sect2" title="5.20. Store both Non-Tor and Tor cookies in a protected jar (dangerous)"><div class="titlepage"><div><div><h3 class="title"><a id="id2979522"></a>5.20. Store both Non-Tor and Tor cookies in a protected jar (dangerous)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.dual_cookie_jars</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`891) </p><p> 892) 893) This setting causes Torbutton to use <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cookie-jar-selector.js" target="_top">@torproject.org/cookie-jar-selector;2</a> to store 894) both Tor and Non-Tor cookies into protected jars. 895) </p><p> 896) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> requirement.`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	897) </p></div><div class="sect2" title="5.21. Manage My Own Cookies (dangerous)"><div class="titlepage"><div><div><h3 class="title"><a id="id2979560"></a>5.21. Manage My Own Cookies (dangerous)</h3></div></div></div><p>Options: None</p><p>This setting disables all Torbutton cookie handling by setting the above 898) cookie prefs all to false.</p></div><div class="sect2" title="5.22. Disable DOM Storage during Tor usage (crucial)"><div class="titlepage"><div><div><h3 class="title"><a id="id2979576"></a>5.22. Disable DOM Storage during Tor usage (crucial)</h3></div></div></div><div class="sect2" title="5.22.1. Do not write Tor/Non-Tor cookies to disk"><div class="titlepage"><div><div><h3 class="title"><a id="id2979578"></a>5.22.1. Do not write Tor/Non-Tor cookies to disk</h3></div></div></div><p>Options:
add torbutton design dir fr... Andrew Lewman authored 14 years ago	899) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.tor_memory_jar</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.nontor_memory_jar</strong></span></td></tr></table><p> 900) </p><p> 901) These settings (contributed by arno) cause Torbutton to set <a class="ulink" href="http://kb.mozillazine.org/Network.cookie.lifetimePolicy" target="_top">network.cookie.lifetimePolicy</a> 902) to 2 during the appropriate Tor state, and to store cookies acquired in that 903) state into a Javascript 904) <a class="ulink" href="http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide:Processing_XML_with_E4X" target="_top">E4X</a> 905) object as opposed to writing them to disk. 906) </p><p> 907) This allows Torbutton to provide an option to preserve a user's 908) cookies while still satisfying the <a class="link" href="#disk">Disk Avoidance</a> 909) requirement. 910) </p></div><p>Option: <span class="command"><strong>extensions.torbutton.disable_domstorage</strong></span> 911) </p><p> 912) 913) This setting causes Torbutton to toggle <span class="command"><strong>dom.storage.enabled</strong></span> during Tor 914) usage to prevent 915) <a class="ulink" href="http://developer.mozilla.org/en/docs/DOM:Storage" target="_top">DOM Storage</a> from 916) being used to store persistent information across Tor states.</p><p> 917) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> requirement.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`918) </p></div><div class="sect2" title="5.23. Clear HTTP Auth on Tor Toggle (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2979679"></a>5.23. Clear HTTP Auth on Tor Toggle (recommended)</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.clear_http_auth</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`919) </p><p> 920) This setting causes Torbutton to call <a class="ulink" href="http://www.oxymoronical.com/experiments/apidocs/interface/nsIHttpAuthManager" target="_top">nsIHttpAuthManager.clearAll()</a> 921) every time Tor is toggled. 922) </p><p> 923) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> requirement.`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`924) </p></div><div class="sect2" title="5.24. Clear cookies on Tor/Non-Tor shutdown"><div class="titlepage"><div><div><h3 class="title"><a id="id2979717"></a>5.24. Clear cookies on Tor/Non-Tor shutdown</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.shutdown_method</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`925) </p><p> This option variable can actually take 3 values: 0, 1, and 2. 0 means no 926) cookie clearing, 1 means clear only during Tor-enabled shutdown, and 2 means 927) clear for both Tor and Non-Tor shutdown. When set to 1 or 2, Torbutton listens 928) for the <a class="ulink" href="http://developer.mozilla.org/en/docs/Observer_Notifications#Application_shutdown" target="_top">quit-application-granted</a> event in`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`929) <code class="function">https://git.torproject.org/checkout/torbutton/master/src/components/crash-observer.js</code> and use <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cookie-jar-selector.js" target="_top">@torproject.org/cookie-jar-selector;2</a>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`930) to clear out all cookies and all cookie jars upon shutdown. </p><p> 931) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> requirement.`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`932) </p></div><div class="sect2" title="5.25. Reload cookie jar/clear cookies on Firefox crash"><div class="titlepage"><div><div><h3 class="title"><a id="id2979772"></a>5.25. Reload cookie jar/clear cookies on Firefox crash</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	933) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.reload_crashed_jar</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.crashed</strong></span></td></tr></table><p> 934) </p><p>This is no longer a user visible option, and is enabled by default. In 935) the event of a crash, the Torbutton <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/crash-observer.js" target="_top">components/crash-observer.js</a> 936) component will notify the Chrome (via the 937) <span class="command"><strong>extensions.torbutton.crashed</strong></span> pref and a <a class="ulink" href="https://developer.mozilla.org/en/NsIPrefBranch2#addObserver.28.29" target="_top">pref 938) observer</a> in 939) the chrome that listens for this update), and Torbutton will load the 940) correct jar for the current Tor state via the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/cookie-jar-selector.js" target="_top">@torproject.org/cookie-jar-selector;2</a> 941) component.</p><p> 942) This setting helps to satisfy the <a class="link" href="#state">State Separation</a> requirement in the event of Firefox 943) crashes.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`944) </p></div><div class="sect2" title="5.26. On crash recovery or session restored startup, restore via: Tor, Non-Tor"><div class="titlepage"><div><div><h3 class="title"><a id="id2979847"></a>5.26. On crash recovery or session restored startup, restore via: Tor, Non-Tor</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	945) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.restore_tor</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.crashed</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.normal_exit</strong></span></td></tr></table><p> 946) </p><p>This option works with the Torbutton <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/crash-observer.js" target="_top">crash-observer.js</a> 947) to set the Tor state after a crash is detected (via the 948) <span class="command"><strong>extensions.torbutton.crashed</strong></span> pref). To confirm for 949) false positives (such as session restore failures, upgrade, normal 950) session restore, etc), Torbutton also sets the pref
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`951) extensions.torbutton.normal_exit during`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`952) Firefox exit and checks this value as well during startup. 953) </p><p> 954) 955) Since the Tor state after a Firefox crash is unknown/indeterminate, this 956) setting helps to satisfy the <a class="link" href="#state">State Separation</a> 957) requirement in the event of Firefox crashes by ensuring all cookies, 958) settings and saved sessions are reloaded from a fixed Tor state. 959)`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`960) </p></div><div class="sect2" title="5.27. On normal startup, set state to: Tor, Non-Tor, Shutdown State"><div class="titlepage"><div><div><h3 class="title"><a id="id2979919"></a>5.27. On normal startup, set state to: Tor, Non-Tor, Shutdown State</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	961) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.startup_state</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.noncrashed</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.normal_exit</strong></span></td></tr></table><p> 962) </p><p>This option also works with the Torbutton <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/crash-observer.js" target="_top">crash-observer.js</a> 963) to set the Tor state after a normal startup is detected (via the 964) <span class="command"><strong>extensions.torbutton.noncrashed</strong></span> pref). To confirm for 965) false positives 966) (such as session restore failures, etc), Torbutton also sets the pref 967) extensions.torbutton.normal_exit in torbutton_uninstall_observer() during 968) Firefox exit and checks this value as well during startup. 969)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`970) </p></div><div class="sect2" title="5.28. Prevent session store from saving Non-Tor/Tor-loaded tabs"><div class="titlepage"><div><div><h3 class="title"><a id="id2979978"></a>5.28. Prevent session store from saving Non-Tor/Tor-loaded tabs</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	971) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.nonontor_sessionstore</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.notor_sessionstore</strong></span></td></tr></table><p> 972) </p><p>If these options are enabled, the <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/components/nsSessionStore3.js" target="_top">replacement nsSessionStore.js</a> 973) component checks the <span class="command"><strong>__tb_tor_fetched</strong></span> tag of tabs before writing them 974) out. If the tag is from a blocked Tor state, the tab is not written to disk. 975) </p><p> 976) This setting helps to satisfy the <a class="link" href="#disk">Disk Avoidance</a> 977) requirement, and also helps to satisfy the <a class="link" href="#state">State Separation</a> requirement in the event of Firefox 978) crashes. 979)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`980) </p></div><div class="sect2" title="5.29. Set user agent during Tor usage (crucial)"><div class="titlepage"><div><div><h3 class="title"><a id="id2980042"></a>5.29. Set user agent during Tor usage (crucial)</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	981) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.set_uagent</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.platform_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.oscpu_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.buildID_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.productsub_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.appname_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.appversion_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.useragent_override</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.useragent_vendor</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.useragent_vendorSub</strong></span></td></tr></table><p> 982) </p><p>On face, user agent switching appears to be straight-forward in Firefox. 983) It provides several options for controlling the browser user agent string: 984) <span class="command"><strong>general.appname.override</strong></span>, 985) <span class="command"><strong>general.appversion.override</strong></span>, 986) <span class="command"><strong>general.platform.override</strong></span>, 987) <span class="command"><strong>general.oscpu.override</strong></span>, 988) <span class="command"><strong>general.productSub.override</strong></span>, 989) <span class="command"><strong>general.buildID.override</strong></span>, 990) <span class="command"><strong>general.useragent.override</strong></span>, 991) <span class="command"><strong>general.useragent.vendor</strong></span>, and 992) <span class="command"><strong>general.useragent.vendorSub</strong></span>. If 993) the Torbutton preference <span class="command"><strong>extensions.torbutton.set_uagent</strong></span> is 994) true, Torbutton copies all of the other above prefs into their corresponding 995) browser preferences during Tor usage.</p><p> 996) 997) It also turns out that it is possible to detect the original Firefox version 998) by <a class="ulink" href="http://ha.ckers.org/blog/20070516/read-firefox-settings-poc/" target="_top">inspecting 999) certain resource:// files</a>. These cases are handled by Torbutton's 1000) <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">content policy</a>. 1001) 1002) </p><p> 1003) This setting helps to satisfy the <a class="link" href="#setpreservation">Anonymity Set Preservation</a> requirement.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1004) </p></div><div class="sect2" title="5.30. Spoof US English Browser"><div class="titlepage"><div><div><h3 class="title"><a id="id2980217"></a>5.30. Spoof US English Browser</h3></div></div></div><p>Options:`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	1005) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.spoof_english</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.spoof_charset</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.spoof_language</strong></span></td></tr></table><p> 1006) </p><p> This option causes Torbutton to set 1007) <span class="command"><strong>general.useragent.locale</strong></span> 1008) <span class="command"><strong>intl.accept_languages</strong></span> to the value specified in 1009) <span class="command"><strong>extensions.torbutton.spoof_locale</strong></span>, 1010) <span class="command"><strong>extensions.torbutton.spoof_charset</strong></span> and 1011) <span class="command"><strong>extensions.torbutton.spoof_language</strong></span> during Tor usage, as 1012) well as hooking <span class="command"><strong>navigator.language</strong></span> via its <a class="link" href="#jshooks" title="5.4. Hook Dangerous Javascript">javascript hooks</a>. 1013) </p><p> 1014) This setting helps to satisfy the <a class="link" href="#setpreservation">Anonymity Set Preservation</a> and <a class="link" href="#location">Location Neutrality</a> requirements.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1015) </p></div><div class="sect2" title="5.31. Don't send referrer during Tor Usage"><div class="titlepage"><div><div><h3 class="title"><a id="id2980310"></a>5.31. Don't send referrer during Tor Usage</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.disable_referer</strong></span>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	1016) </p><p> 1017) This option causes Torbutton to set <a class="ulink" href="http://kb.mozillazine.org/Network.http.sendSecureXSiteReferrer" target="_top">network.http.sendSecureXSiteReferrer</a> and 1018) <a class="ulink" href="http://kb.mozillazine.org/Network.http.sendRefererHeader" target="_top">network.http.sendRefererHeader</a> during Tor usage.</p><p> 1019) This setting also does not directly satisfy any Torbutton requirement, but 1020) some may desire to mask their referrer for general privacy concerns.
Update design doc for 1.2.5. Mike Perry authored 14 years ago	1021) </p></div><div class="sect2" title="5.32. Strip platform and language off of Google Search Box queries"><div class="titlepage"><div><div><h3 class="title"><a id="id2980350"></a>5.32. Strip platform and language off of Google Search Box queries</h3></div></div></div><p>Option: <span class="command"><strong>extensions.torbutton.fix_google_srch</strong></span> 1022) </p><p> 1023) 1024) This option causes Torbutton to use the <a class="ulink" href="https://wiki.mozilla.org/Search_Service:API" target="_top">@mozilla.org/browser/search-service;1</a> 1025) component to wrap the Google search plugin. On many platforms, notably Debian 1026) and Ubuntu, the Google search plugin is set to reveal a lot of language and 1027) platform information. This setting strips off that info while Tor is enabled. 1028) 1029) </p><p> 1030) This setting helps Torbutton to fulfill its <a class="link" href="#setpreservation">Anonymity Set Preservation</a> requirement. 1031) </p></div><div class="sect2" title="5.33. Automatically use an alternate search engine when presented with a Google Captcha"><div class="titlepage"><div><div><h3 class="title"><a id="id2980391"></a>5.33. Automatically use an alternate search engine when presented with a 1032) Google Captcha</h3></div></div></div><p>Options: 1033) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.asked_google_captcha</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.dodge_google_captcha</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.google_redir_url</strong></span></td></tr></table><p> 1034) </p><p> 1035) 1036) Google's earch engine has rate limiting features that cause it to 1037) <a class="ulink" href="http://googleonlinesecurity.blogspot.com/2007/07/reason-behind-were-sorry-message.html" target="_top">present 1038) captchas</a> and sometimes even outright ban IPs that issue large numbers 1039) of search queries, especially if a lot of these queries appear to be searching 1040) for software vulnerabilities or unprotected comment areas. 1041) 1042) </p><p> 1043) 1044) Despite multiple discussions with Google, we were unable to come to a solution 1045) or any form of compromise that would reduce the number of captchas and 1046) outright bans seen by Tor users issuing regular queries. 1047) 1048) </p><p> 1049) As a result, we've implemented this option as an <a class="ulink" href="https://developer.mozilla.org/en/XUL_School/Intercepting_Page_Loads#HTTP_Observers" target="_top">'http-on-modify-request'</a> 1050) http observer to optionally redirect banned or captcha-triggering Google 1051) queries to search engines that do not rate limit Tor users. The current 1052) options are ixquick.com, bing.com, yahoo.com and scroogle.org. These are 1053) encoded in the preferences 1054) <span class="command"><strong>extensions.torbutton.redir_url.[1-4]</strong></span>. 1055) 1056) </p></div><div class="sect2" title="5.34. Store SSL/CA Certs in separate jars for Tor/Non-Tor (recommended)"><div class="titlepage"><div><div><h3 class="title"><a id="id2980471"></a>5.34. Store SSL/CA Certs in separate jars for Tor/Non-Tor (recommended)</h3></div></div></div><p>Options:
add torbutton design dir fr... Andrew Lewman authored 14 years ago	1057) </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>extensions.torbutton.jar_certs</strong></span></td></tr><tr><td><span class="command"><strong>extensions.torbutton.jar_ca_certs</strong></span></td></tr></table><p> 1058) </p><p> 1059) 1060) These settings govern if Torbutton attempts to isolate the user's SSL 1061) certificates into separate jars for each Tor state. This isolation is 1062) implemented in <code class="function">torbutton_jar_certs()</code> in <a class="ulink" href="https://git.torproject.org/checkout/torbutton/master/src/chrome/content/torbutton.js" target="_top">chrome/content/torbutton.js</a>, 1063) which calls <code class="function">torbutton_jar_cert_type()</code> and 1064) <code class="function">torbutton_unjar_cert_type()</code> for each certificate type in 1065) the <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/security/nsscertcache;1" target="_top">@mozilla.org/security/nsscertcache;1</a>. 1066) Certificates are deleted from and imported to the <a class="ulink" href="http://www.oxymoronical.com/experiments/xpcomref/applications/Firefox/3.5/components/%40mozilla.org/security/x509certdb;1" target="_top">@mozilla.org/security/x509certdb;1</a>. 1067) </p><p> 1068) The first time this pref is used, a backup of the user's certificates is 1069) created in their profile directory under the name 1070) <code class="filename">cert8.db.bak</code>. This file can be copied back to 1071) <code class="filename">cert8.db</code> to fully restore the original state of the 1072) user's certificates in the event of any error. 1073) </p><p> 1074) Since exit nodes and malicious sites can insert content elements sourced to 1075) specific SSL sites to query if a user has a certain certificate, 1076) this setting helps to satisfy the <a class="link" href="#state">State 1077) Separation</a> requirement of Torbutton. Unfortunately, <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=435159" target="_top">Firefox Bug 1078) 435159</a> prevents it from functioning correctly in the event of rapid Tor toggle, so it 1079) is currently not exposed via the preferences UI. 1080) 1081) </p></div></div><div class="sect1" title="6. Relevant Firefox Bugs"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="FirefoxBugs"></a>6. Relevant Firefox Bugs</h2></div></div></div><p> 1082) 1083) </p><div class="sect2" title="6.1. Bugs impacting security"><div class="titlepage"><div><div><h3 class="title"><a id="FirefoxSecurity"></a>6.1. Bugs impacting security</h3></div></div></div><p> 1084) 1085) Torbutton has to work around a number of Firefox bugs that impact its 1086) security. Most of these are mentioned elsewhere in this document, but they 1087) have also been gathered here for reference. Several of these have fixes in 1088) Firefox3.0/trunk, but are listed because they still have not been backported 1089) to FF2.0. In order of decreasing severity, they are: 1090) 1091) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=392274" target="_top">Bug 392274 - Timezone 1092) config/chrome API</a><p> 1093) 1094) The lack of a config or API to configure the timezone requires Torbutton to 1095) <a class="link" href="#jshooks" title="5.4. Hook Dangerous Javascript">insert client content window javascript</a> to hook 1096) the Date object. Additionally, a way to <a class="ulink" href="http://pseudo-flaw.net/tor/torbutton/unmask-date.html" target="_top">remove the Date 1097) hooks</a> was discovered by Greg Fleischer. Worse, on Firefox 3, 1098) javascript sandboxing prevents most of the javascript hooks from being 1099) installed, including the Date hooks. On Windows and Linux, you can set the TZ 1100) environment variable to "UTC" as a workaround. Firefox will obey this 1101) environment variable for your Timezone on those platforms, but on Windows this 1102) does not take effect until browser restart. A fix for this has landed in 1103) Firefox 3.5, but still has not been backported to Firefox 3.0. The lack of an 1104) easy way to reliably spoof the timezone interferes with Torbutton's ability to 1105) fulfill its <a class="link" href="#location">Location Neutrality</a> requirement. 1106) 1107) 1108) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=435159" target="_top">Bug 435159 - 1109) nsNSSCertificateDB::DeleteCertificate has race conditions</a><p> 1110) 1111) In Torbutton 1.2.0rc1, code was added to attempt to isolate SSL certificates 1112) the user has installed. Unfortunately, the method call to delete a certificate 1113) from the current certificate database acts lazily: it only sets a variable 1114) that marks a cert for deletion later, and it is not cleared if that 1115) certificate is re-added. This means that if the Tor state is toggled quickly, 1116) that certificate could remain present until it is re-inserted (causing an 1117) error dialog), and worse, it would still be deleted after that. The lack of 1118) this functionality is considered a Torbutton security bug because cert 1119) isolation is considered a <a class="link" href="#state">State Separation</a> 1120) feature. 1121) 1122) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=409737" target="_top">Bug 409737 - 1123) javascript.enabled and docShell.allowJavascript do not disable all event 1124) handlers</a><p> 1125) 1126) This bug allows pages to execute javascript via addEventListener and perhaps 1127) other callbacks. In order to prevent this bug from enabling an attacker to 1128) break the <a class="link" href="#isolation">Network Isolation</a> requirement, 1129) Torbutton 1.1.13 began blocking popups and history manipulation from different 1130) Tor states. So long as there are no ways to open popups or redirect the user 1131) to a new page, the <a class="link" href="#contentpolicy" title="@torproject.org/cssblocker;1 - components/cssblocker.js">Torbutton content 1132) policy</a> should block Javascript network access. However, if there are 1133) ways to open popups or perform redirects such that Torbutton cannot block 1134) them, pages may still have free reign to break that requirement and reveal a 1135) user's original IP address. 1136) 1137) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=448743" target="_top">Bug 448743 - 1138) Decouple general.useragent.locale from spoofing of navigator.language</a><p> 1139) 1140) Currently, Torbutton spoofs the <span class="command"><strong>navigator.language</strong></span> 1141) attribute via <a class="link" href="#jshooks" title="5.4. Hook Dangerous Javascript">Javascript hooks</a>. Unfortunately, 1142) these do not work on Firefox 3. It would be ideal to have 1143) a pref to set this value (something like a 1144) <span class="command"><strong>general.useragent.override.locale</strong></span>), 1145) to avoid fragmenting the anonymity set of users of foreign locales. This issue 1146) impedes Torbutton from fully meeting its <a class="link" href="#setpreservation">Anonymity Set Preservation</a> 1147) requirement on Firefox 3. 1148) 1149) </p></li></ol></div></div><div class="sect2" title="6.2. Bugs blocking functionality"><div class="titlepage"><div><div><h3 class="title"><a id="FirefoxWishlist"></a>6.2. Bugs blocking functionality</h3></div></div></div><p> 1150) The following bugs impact Torbutton and similar extensions' functionality. 1151) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=445696" target="_top">Bug 445696 - 1152) Extensions cannot determine if firefox is fullScreen</a><p> 1153) 1154) The windowState property of <a class="ulink" href="https://developer.mozilla.org/en/XUL/window" target="_top">ChromeWindows</a> does not accurately reflect the true 1155) state of the window in some cases on Linux. This causes Torbutton to attempt 1156) to resize maximized and minimized windows when it should not. 1157) 1158) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=290456" target="_top">Bug 290456 - 1159) Block/clear Flash MX "cookies" as well</a><p> 1160) 1161) Today, it is possible to allow plugins if you have a transparent proxy such as 1162) <a class="ulink" href="http://anonymityanywhere.com/incognito/" target="_top">Incognito</a> to prevent proxy bypass. However, flash cookies can still be used to 1163) link your Tor and Non-Tor activity, and this reveal your IP to an adversary 1164) that does so. This can be solved by manually removing your flash cookies (like 1165) <a class="ulink" href="https://addons.mozilla.org/en-US/firefox/addon/6623" target="_top">BetterPrivacy</a> does), but 1166) it would be nice if there was a standard way to do this from a Firefox API. 1167) 1168) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=417869" target="_top">Bug 417869 - 1169) Browser context is difficult to obtain from many XPCOM callbacks</a><p> 1170) 1171) It is difficult to determine which tabbrowser many XPCOM callbacks originate 1172) from, and in some cases absolutely no context information is provided at all. 1173) While this doesn't have much of an effect on Torbutton, it does make writing 1174) extensions that would like to do per-tab settings and content filters (such as 1175) FoxyProxy) difficult to impossible to implement securely. 1176) 1177) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=418321" target="_top">Bug 418321 - 1178) Components do not expose disk interfaces</a><p> 1179) 1180) Several components currently provide no way of reimplementing their disk 1181) access to easily satisfy Torbutton's <a class="link" href="#disk">Disk 1182) Avoidance</a> requirements. Workarounds exist, but they are <a class="link" href="#sessionstore" title="@mozilla.org/browser/sessionstore;1 - components/nsSessionStore36.js">clunky</a>, and 1183) some of them involve disabling functionality during Tor usage. 1184) 1185) </p></li></ol></div></div><div class="sect2" title="6.3. Low Priority Bugs"><div class="titlepage"><div><div><h3 class="title"><a id="FirefoxMiscBugs"></a>6.3. Low Priority Bugs</h3></div></div></div><p> 1186) The following bugs have an effect upon Torbutton, but are superseded by more 1187) practical and more easily fixable variant bugs above; or have stable, simple 1188) workarounds. 1189) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=435151" target="_top">Bug 435151 - XPCSafeJSObjectWrapper breaks evalInSandbox</a><p> 1190) 1191) Under Firefox 3, the XPCSafeJSObjectWrapper breaks when you try to use 1192) constructors of classes defined from within the scope of the sandbox, among 1193) other things. This prevents Torbutton from applying the Timezone hooks under 1194) Firefox 3, but a better solution for Torbutton's specific date hooking needs 1195) would be a fix for the above mentioned Bug 392274. Of course, many more 1196) extensions may be interested in the sandbox hooking functionality working 1197) properly though. 1198) 1199) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=440892" target="_top">Bug 440892 - 1200) network.protocol-handler.warn-external are ignored</a><p> 1201) 1202) Sometime in the Firefox 3 development cycle, the preferences that governed 1203) warning a user when external apps were launched got disconnected from the code 1204) that does the launching. Torbutton depended on these prefs to prevent websites 1205) from launching specially crafted documents and application arguments that 1206) caused Proxy Bypass. We currently work around this issue by <a class="link" href="#appblocker" title="@mozilla.org/uriloader/external-protocol-service;1 , @mozilla.org/uriloader/external-helper-app-service;1, and @mozilla.org/mime;1 - components/external-app-blocker.js">wrapping the app launching components</a> to present a 1207) popup before launching external apps while Tor is enabled. While this works, 1208) it would be nice if these prefs were either fixed or removed. 1209) 1210) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=437014" target="_top">Bug 437014 - 1211) nsIContentPolicy::shouldLoad no longer called for favicons</a><p> 1212) 1213) Firefox 3.0 stopped calling the shouldLoad call of content policy for favicon 1214) loads. Torbutton had relied on this call to block favicon loads for opposite 1215) Tor states. The workaround it employs for Firefox 3 is to cancel the request 1216) when it arrives in the <span class="command"><strong>torbutton_http_observer</strong></span> used for 1217) blocking full page plugin loads. This seems to work just fine, but is a bit 1218) dirty. 1219) 1220) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=418986" target="_top">Bug 418986 - window.screen 1221) provides a large amount of identifiable information</a><p> 1222) 1223) As <a class="link" href="#fingerprinting">mentioned above</a>, a large amount of 1224) information is available from <a class="ulink" href="http://developer.mozilla.org/en/docs/DOM:window.screen" target="_top">window.screen</a>. 1225) Currently, there is no way to obscure this information without Javascript 1226) hooking. This bug is a feature request to provide some other method to change 1227) these values. 1228) 1229) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=309524" target="_top">Bug 309524</a> 1230) and <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=380556" target="_top">Bug 1231) 380556</a> - nsIContentPolicy::shouldProcess is not called. 1232) <p> 1233) 1234) This is a call that would be useful to develop a better workaround for the 1235) allowPlugins issue above. If the content policy were called before a URL was 1236) handed over to a plugin or helper app, it would make the workaround for the 1237) above allowPlugins bug a lot cleaner. Obviously this bug is not as severe as 1238) the others though, but it might be nice to have this API as a backup. 1239) 1240) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=401296" target="_top">Bug 401296 - docShell.allowPlugins 1241) not honored for direct links</a> (Perhaps subset of <a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=282106" target="_top">Bug 282106</a>?) 1242) <p> 1243) 1244) Similar to the javascript plugin disabling attribute, the plugin disabling 1245) attribute is also not perfect — it is ignored for direct links to plugin 1246) handled content, as well as meta-refreshes to plugin handled content. This 1247) requires Torbutton to listen to a number of different http events to intercept 1248) plugin-related mime type URLs and cancel their requests. Again, since plugins 1249) are quite horrible about obeying proxy settings, loading a plugin pretty much 1250) ensures a way to break the <a class="link" href="#isolation">Network Isolation</a> 1251) requirement and reveal a user's original IP address. Torbutton's code to 1252) perform this workaround has been subverted at least once already by Kyle 1253) Williams. 1254) 1255) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=448747" target="_top">Bug 448747 - 1256) Provide Mechanism to clear TLS Session IDs</a><p> 1257) 1258) As <a class="link" href="#browseroverlay" title="3.1. Browser Overlay - torbutton.xul">mentioned above</a>, Torbutton currently 1259) toggles <span class="command"><strong>security.enable_ssl2</strong></span> to clear the SSL 1260) Session ID cache via the pref observer at <a class="ulink" href="http://mxr.mozilla.org/security/source/security/manager/ssl/src/nsNSSComponent.cpp#2134" target="_top">nsNSSComponent.cpp 1261) line 2134</a>. This is an arcane and potentially fragile fix. It would be 1262) better if there were a more standard interface for accomplishing the same 1263) thing. 1264) 1265) </p></li><li class="listitem"><a class="ulink" href="https://bugzilla.mozilla.org/show_bug.cgi?id=419598" target="_top">Bug 419598 - 'var 1266) Date' is deletable</a><p> 1267) 1268) Based on Page 62 of the <a class="ulink" href="http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf" target="_top">ECMA-262 1269) Javascript spec</a>, it seems like it should be possible to do something 1270) like the following to prevent the Date object from being unmasked: 1271) </p><pre class="screen"> 1272) with(window) { 1273) var Date = fakeDate; 1274) var otherVariable = 42; 1275) } 1276) 1277) delete window.Date; // Should fail. Instead succeeds, revealing original Date. 1278) delete window.otherVariable; // Fails, leaving window.otherVariable set to 42. 1279) </pre><p> 1280) 1281) From the ECMA-262 spec: 1282) 1283) </p><div class="blockquote"><blockquote class="blockquote"> 1284) If the variable statement occurs inside a FunctionDeclaration, the variables 1285) are defined with function-local scope in that function, as described in 1286) s10.1.3. Otherwise, they are defined with global scope (that is, they are 1287) created as members of the global object, as described in 10.1.3) using 1288) property attributes { DontDelete }. Variables are created when the execution 1289) scope is entered. A Block does not define a new execution scope. Only Program 1290) and FunctionDeclaration produce a new scope. Variables are initialized to 1291) undefined when created. A variable with an Initialiser is assigned the value 1292) of its AssignmentExpression when the VariableStatement is executed, not when 1293) the variable is created. 1294) </blockquote></div><p> 1295) 1296) In fact, this is exactly how the with statement with a variable declaration 1297) behaves <span class="emphasis"><em>for all other variables other than ones that shadow system 1298) variables</em></span>. Some variables (such as 1299) <span class="command"><strong>window.screen</strong></span>, and <span class="command"><strong>window.history</strong></span>) can't 1300) even be shadowed in this way, and give an error about lacking a setter. If 1301) such shadowing were possible, it would greatly simplify the Javascript hooking 1302) code, which currently relies on undocumented semantics of 1303) <span class="command"><strong>__proto__</strong></span> to copy the original values in the event of a 1304) delete. This <span class="command"><strong>__proto__</strong></span> hack unfortunately does not work for 1305) the Date object though. 1306) 1307) </p></li></ol></div></div></div><div class="sect1" title="7. Testing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="TestPlan"></a>7. Testing</h2></div></div></div><p> 1308) 1309) The purpose of this section is to cover all the known ways that Tor browser 1310) security can be subverted from a penetration testing perspective. The hope 1311) is that it will be useful both for creating a "Tor Safety Check" 1312) page, and for developing novel tests and actively attacking Torbutton with the 1313) goal of finding vulnerabilities in either it or the Mozilla components, 1314) interfaces and settings upon which it relies. 1315) 1316) </p><div class="sect2" title="7.1. Single state testing"><div class="titlepage"><div><div><h3 class="title"><a id="SingleStateTesting"></a>7.1. Single state testing</h3></div></div></div><p> 1317) 1318) Torbutton is a complicated piece of software. During development, changes to 1319) one component can affect a whole slough of unrelated features. A number of 1320) aggregated test suites exist that can be used to test for regressions in 1321) Torbutton and to help aid in the development of Torbutton-like addons and 1322) other privacy modifications of other browsers. Some of these test suites exist 1323) as a single automated page, while others are a series of pages you must visit 1324) individually. They are provided here for reference and future regression 1325) testing, and also in the hope that some brave soul will one day decide to 1326) combine them into a comprehensive automated test suite. 1327) 1328) </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="http://decloak.net/" target="_top">Decloak.net</a><p> 1329) 1330) Decloak.net is the canonical source of plugin and external-application based 1331) proxy-bypass exploits. It is a fully automated test suite maintained by <a class="ulink" href="http://digitaloffense.net/" target="_top">HD Moore</a> as a service for people to 1332) use to test their anonymity systems. 1333) 1334) </p></li><li class="listitem"><a class="ulink" href="http://deanonymizer.com/" target="_top">Deanonymizer.com</a><p> 1335) 1336) Deanonymizer.com is another automated test suite that tests for proxy bypass 1337) and other information disclosure vulnerabilities. It is maintained by Kyle 1338) Williams, the author of <a class="ulink" href="http://www.janusvm.com/" target="_top">JanusVM</a> 1339) and <a class="ulink" href="http://www.januspa.com/" target="_top">JanusPA</a>. 1340) 1341) </p></li><li class="listitem"><a class="ulink" href="https://www.jondos.de/en/anontest" target="_top">JonDos 1342) AnonTest</a><p> 1343) 1344) The <a class="ulink" href="https://www.jondos.de" target="_top">JonDos people</a> also provide an 1345) anonymity tester. It is more focused on HTTP headers than plugin bypass, and 1346) points out a couple of headers Torbutton could do a better job with 1347) obfuscating. 1348) 1349) </p></li><li class="listitem"><a class="ulink" href="http://browserspy.dk" target="_top">Browserspy.dk</a><p> 1350) 1351) Browserspy.dk provides a tremendous collection of browser fingerprinting and 1352) general privacy tests. Unfortunately they are only available one page at a 1353) time, and there is not really solid feedback on good vs bad behavior in 1354) the test results. 1355) 1356) </p></li><li class="listitem"><a class="ulink" href="http://analyze.privacy.net/" target="_top">Privacy 1357) Analyzer</a><p> 1358) 1359) The Privacy Analyzer provides a dump of all sorts of browser attributes and 1360) settings that it detects, including some information on your origin IP 1361) address. Its page layout and lack of good vs bad test result feedback makes it 1362) not as useful as a user-facing testing tool, but it does provide some 1363) interesting checks in a single page. 1364) 1365) </p></li><li class="listitem"><a class="ulink" href="http://ha.ckers.org/mr-t/" target="_top">Mr. T</a><p> 1366) 1367) Mr. T is a collection of browser fingerprinting and deanonymization exploits 1368) discovered by the <a class="ulink" href="http://ha.ckers.org" target="_top">ha.ckers.org</a> crew 1369) and others. It is also not as user friendly as some of the above tests, but it 1370) is a useful collection. 1371) 1372) </p></li><li class="listitem">Gregory Fleischer's <a class="ulink" href="http://pseudo-flaw.net/content/tor/torbutton/" target="_top">Torbutton</a> and 1373) <a class="ulink" href="http://pseudo-flaw.net/content/defcon/dc-17-demos/d.html" target="_top">Defcon 1374) 17</a> Test Cases 1375) <p> 1376) 1377) Gregory Fleischer has been hacking and testing Firefox and Torbutton privacy 1378) issues for the past 2 years. He has an excellent collection of all his test 1379) cases that can be used for regression testing. In his Defcon work, he 1380) demonstrates ways to infer Firefox version based on arcane browser properties. 1381) We are still trying to determine the best way to address some of those test 1382) cases. 1383) 1384) </p></li><li class="listitem"><a class="ulink" href="https://torcheck.xenobite.eu/index.php" target="_top">Xenobite's 1385) TorCheck Page</a><p> 1386) 1387) This page checks to ensure you are using a valid Tor exit node and checks for 1388) some basic browser properties related to privacy. It is not very fine-grained 1389) or complete, but it is automated and could be turned into something useful 1390) with a bit of work. 1391) 1392) </p></li></ol></div><p>
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1393) </p></div><div class="sect2" title="7.2. Multi-state testing"><div class="titlepage"><div><div><h3 class="title"><a id="id2981478"></a>7.2. Multi-state testing</h3></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`1394) 1395) The tests in this section are geared towards a page that would instruct the 1396) user to toggle their Tor state after the fetch and perform some operations: 1397) mouseovers, stray clicks, and potentially reloads. 1398)`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1399) </p><div class="sect3" title="Cookies and Cache Correlation"><div class="titlepage"><div><div><h4 class="title"><a id="id2981490"></a>Cookies and Cache Correlation</h4></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	1400) The most obvious test is to set a cookie, ask the user to toggle tor, and then 1401) have them reload the page. The cookie should no longer be set if they are 1402) using the default Torbutton settings. In addition, it is possible to leverage 1403) the cache to <a class="ulink" href="http://crypto.stanford.edu/sameorigin/safecachetest.html" target="_top">store unique 1404) identifiers</a>. The default settings of Torbutton should also protect 1405) against these from persisting across Tor Toggle. 1406)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1407) </p></div><div class="sect3" title="Javascript timers and event handlers"><div class="titlepage"><div><div><h4 class="title"><a id="id2981513"></a>Javascript timers and event handlers</h4></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	`1408) 1409) Javascript can set timers and register event handlers in the hopes of fetching 1410) URLs after the user has toggled Torbutton.`
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1411) </p></div><div class="sect3" title="CSS Popups and non-script Dynamic Content"><div class="titlepage"><div><div><h4 class="title"><a id="id2981526"></a>CSS Popups and non-script Dynamic Content</h4></div></div></div><p>`
add torbutton design dir fr... Andrew Lewman authored 14 years ago	1412) 1413) Even if Javascript is disabled, CSS is still able to 1414) <a class="ulink" href="http://www.tjkdesign.com/articles/css%20pop%20ups/" target="_top">create popup-like 1415) windows</a> 1416) via the 'onmouseover' CSS attribute, which can cause arbitrary browser 1417) activity as soon as the mouse enters into the content window. It is also 1418) possible for meta-refresh tags to set timers long enough to make it likely 1419) that the user has toggled Tor before fetching content. 1420) 1421) </p></div></div><div class="sect2" title="7.3. Active testing (aka How to Hack Torbutton)"><div class="titlepage"><div><div><h3 class="title"><a id="HackTorbutton"></a>7.3. Active testing (aka How to Hack Torbutton)</h3></div></div></div><p> 1422) 1423) The idea behind active testing is to discover vulnerabilities in Torbutton to 1424) bypass proxy settings, run script in an opposite Tor state, store unique 1425) identifiers, leak location information, or otherwise violate <a class="link" href="#requirements" title="1.2. Torbutton Requirements">its requirements</a>. Torbutton has ventured out 1426) into a strange and new security landscape. It depends on Firefox mechanisms 1427) that haven't necessarily been audited for security, certainly not for the 1428) threat model that Torbutton seeks to address. As such, it and the interfaces 1429) it depends upon still need a 'trial by fire' typical of new technologies. This 1430) section of the document was written with the intention of making that period 1431) as fast as possible. Please help us get through this period by considering 1432) these attacks, playing with them, and reporting what you find (and potentially 1433) submitting the test cases back to be run in the standard batch of Torbutton 1434) tests. 1435)
Update design doc for 1.2.5. Mike Perry authored 14 years ago	`1436) </p><div class="sect3" title="Some suggested vectors to investigate"><div class="titlepage"><div><div><h4 class="title"><a id="id2981580"></a>Some suggested vectors to investigate</h4></div></div></div><p>`