Author: mikeperry Date: 2011-10-05 06:25:27 +0000 (Wed, 05 Oct 2011) New Revision: 25150
Modified: website/trunk/projects/torbrowser/design/index.html.en Log: Describe our efforts against flash in TBB doc.
Modified: website/trunk/projects/torbrowser/design/index.html.en =================================================================== --- website/trunk/projects/torbrowser/design/index.html.en 2011-10-05 05:48:34 UTC (rev 25149) +++ website/trunk/projects/torbrowser/design/index.html.en 2011-10-05 06:25:27 UTC (rev 25150) @@ -1,6 +1,6 @@ <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> -<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>The Design and Implementation of the Tor Browser [DRAFT]</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div class="article" title="The Design and Implementation of the Tor Browser [DRAFT]"><div class="titlepage"><div><div><h2 class="title"><a id="design"></a>The Design and Implementation of the Tor Browser [DRAFT]</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#torproject org">mikeperry#torproject org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Erinn</span> <span class="surname">Clark</span></h3><div class="affiliation"><div class="address"><p><code class= "email"><<a class="email" href="mailto:erinn#torproject org">erinn#torproject org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Steven</span> <span class="surname">Murdoch</span></h3><div class="affiliation"><div class="address"><p><code class="email"><<a class="email" href="mailto:sjmurdoch#torproject org">sjmurdoch#torproject org</a>></code></p></div></div></div></div><div><p class="pubdate">Oct 4 2011</p></div></div><hr /></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="#id2748505">1. Introduction</a></span></dt><dd><dl><dt><span class="sect2"><a href="#adversary">1.1. Adversary Model</a></span></dt></dl></dd><dt><span class="sect1"><a href="#DesignRequirements">2. Design Requirements and Philosophy</a></span></dt><dd><dl><dt><span class="sect2"><a href="#security">2.1. Security Requirements</a></span></dt><dt><span class="sect2"><a href="#privacy">2.2. Pri vacy Requirements</a></span></dt><dt><span class="sect2"><a href="#philosophy">2.3. Philosophy</a></span></dt></dl></dd><dt><span class="sect1"><a href="#Implementation">3. Implementation</a></span></dt><dd><dl><dt><span class="sect2"><a href="#proxy-obedience">3.1. Proxy Obedience</a></span></dt><dt><span class="sect2"><a href="#state-separation">3.2. State Separation</a></span></dt><dt><span class="sect2"><a href="#disk-avoidance">3.3. Disk Avoidance</a></span></dt><dt><span class="sect2"><a href="#app-data-isolation">3.4. Application Data Isolation</a></span></dt><dt><span class="sect2"><a href="#identifier-linkability">3.5. Cross-Origin Identifier Unlinkability</a></span></dt><dt><span class="sect2"><a href="#fingerprinting-linkability">3.6. Cross-Origin Fingerprinting Unlinkability</a></span></dt><dt><span class="sect2"><a href="#new-identity">3.7. Long-Term Unlinkability via "New Identity" button</a></span></dt><dt><span class="sect2"><a href="#click-to-play">3.8. Clic k-to-play for plugins and invasive content</a></span></dt><dt><span class="sect2"><a href="#firefox-patches">3.9. Description of Firefox Patches</a></span></dt></dl></dd><dt><span class="sect1"><a href="#Packaging">4. Packaging</a></span></dt><dd><dl><dt><span class="sect2"><a href="#build-security">4.1. Build Process Security</a></span></dt><dt><span class="sect2"><a href="#addons">4.2. External Addons</a></span></dt><dt><span class="sect2"><a href="#prefs">4.3. Pref Changes</a></span></dt><dt><span class="sect2"><a href="#update-mechanism">4.4. Update Security</a></span></dt></dl></dd><dt><span class="sect1"><a href="#Testing">5. Testing</a></span></dt><dd><dl><dt><span class="sect2"><a href="#SingleStateTesting">5.1. Single state testing</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="id2748505"></a>1. Introduction</h2></div></div></div><p> +<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>The Design and Implementation of the Tor Browser [DRAFT]</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div class="article" title="The Design and Implementation of the Tor Browser [DRAFT]"><div class="titlepage"><div><div><h2 class="title"><a id="design"></a>The Design and Implementation of the Tor Browser [DRAFT]</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#torproject org">mikeperry#torproject org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Erinn</span> <span class="surname">Clark</span></h3><div class="affiliation"><div class="address"><p><code class= "email"><<a class="email" href="mailto:erinn#torproject org">erinn#torproject org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Steven</span> <span class="surname">Murdoch</span></h3><div class="affiliation"><div class="address"><p><code class="email"><<a class="email" href="mailto:sjmurdoch#torproject org">sjmurdoch#torproject org</a>></code></p></div></div></div></div><div><p class="pubdate">Oct 4 2011</p></div></div><hr /></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="#id2857732">1. Introduction</a></span></dt><dd><dl><dt><span class="sect2"><a href="#adversary">1.1. Adversary Model</a></span></dt></dl></dd><dt><span class="sect1"><a href="#DesignRequirements">2. Design Requirements and Philosophy</a></span></dt><dd><dl><dt><span class="sect2"><a href="#security">2.1. Security Requirements</a></span></dt><dt><span class="sect2"><a href="#privacy">2.2. Pri vacy Requirements</a></span></dt><dt><span class="sect2"><a href="#philosophy">2.3. Philosophy</a></span></dt></dl></dd><dt><span class="sect1"><a href="#Implementation">3. Implementation</a></span></dt><dd><dl><dt><span class="sect2"><a href="#proxy-obedience">3.1. Proxy Obedience</a></span></dt><dt><span class="sect2"><a href="#state-separation">3.2. State Separation</a></span></dt><dt><span class="sect2"><a href="#disk-avoidance">3.3. Disk Avoidance</a></span></dt><dt><span class="sect2"><a href="#app-data-isolation">3.4. Application Data Isolation</a></span></dt><dt><span class="sect2"><a href="#identifier-linkability">3.5. Cross-Origin Identifier Unlinkability</a></span></dt><dt><span class="sect2"><a href="#fingerprinting-linkability">3.6. Cross-Origin Fingerprinting Unlinkability</a></span></dt><dt><span class="sect2"><a href="#new-identity">3.7. Long-Term Unlinkability via "New Identity" button</a></span></dt><dt><span class="sect2"><a href="#click-to-play">3.8. Clic k-to-play for plugins and invasive content</a></span></dt><dt><span class="sect2"><a href="#firefox-patches">3.9. Description of Firefox Patches</a></span></dt></dl></dd><dt><span class="sect1"><a href="#Packaging">4. Packaging</a></span></dt><dd><dl><dt><span class="sect2"><a href="#build-security">4.1. Build Process Security</a></span></dt><dt><span class="sect2"><a href="#addons">4.2. External Addons</a></span></dt><dt><span class="sect2"><a href="#prefs">4.3. Pref Changes</a></span></dt><dt><span class="sect2"><a href="#update-mechanism">4.4. Update Security</a></span></dt></dl></dd><dt><span class="sect1"><a href="#Testing">5. Testing</a></span></dt><dd><dl><dt><span class="sect2"><a href="#SingleStateTesting">5.1. Single state testing</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="id2857732"></a>1. Introduction</h2></div></div></div><p>
This document describes the <a class="link" href="#adversary" title="1.1. Adversary Model">adversary model</a>, <a class="link" href="#DesignRequirements" title="2. Design Requirements and Philosophy">design requirements</a>, @@ -417,13 +417,13 @@ Tor Browser State is separated from existing browser state through use of a custom Firefox profile. Furthermore, plugins are disabled, which prevents Flash cookies from leaking from a pre-existing Flash directory. - </p></div><div class="sect2" title="3.3. Disk Avoidance"><div class="titlepage"><div><div><h3 class="title"><a id="disk-avoidance"></a>3.3. Disk Avoidance</h3></div></div></div><div class="sect3" title="Design Goal:"><div class="titlepage"><div><div><h4 class="title"><a id="id2777452"></a>Design Goal:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> + </p></div><div class="sect2" title="3.3. Disk Avoidance"><div class="titlepage"><div><div><h3 class="title"><a id="disk-avoidance"></a>3.3. Disk Avoidance</h3></div></div></div><div class="sect3" title="Design Goal:"><div class="titlepage"><div><div><h4 class="title"><a id="id2886678"></a>Design Goal:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> Tor Browser MUST (at user option) prevent all disk records of browser activity. The user should be able to optionally enable URL history and other history features if they so desire. Once we <a class="ulink" href="https://trac.torproject.org/projects/tor/ticket/3100" target="_top">simplify the preferences interface</a>, we will likely just enable Private Browsing mode by default to handle this goal. - </blockquote></div></div><div class="sect3" title="Implementation Status:"><div class="titlepage"><div><div><h4 class="title"><a id="id2765334"></a>Implementation Status:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> + </blockquote></div></div><div class="sect3" title="Implementation Status:"><div class="titlepage"><div><div><h4 class="title"><a id="id2874561"></a>Implementation Status:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> For now, Tor Browser blocks write access to the disk through Torbutton using several Firefox preferences.
@@ -488,7 +488,7 @@ context-menu option to drill down into specific types of state or permissions. An example of this simplification can be seen in Figure 1.
- </p><div class="figure"><a id="id2758612"></a><p class="title"><b>Figure 1. Improving the Privacy UI</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="CookieManagers.png" align="middle" alt="Improving the Privacy UI" /></div><div class="caption"><p></p> + </p><div class="figure"><a id="id2867838"></a><p class="title"><b>Figure 1. Improving the Privacy UI</b></p><div class="figure-contents"><div class="mediaobject" align="center"><img src="CookieManagers.png" align="middle" alt="Improving the Privacy UI" /></div><div class="caption"><p></p>
On the left is the standard Firefox cookie manager. On the right is a mock-up of how isolating identifiers to the URL bar origin might simplify the privacy @@ -571,6 +571,19 @@ Because it is isolated to third party domain as opposed to top level url bar origin, we entirely disable DOM storage as a stopgap to ensure unlinkability.
+ </p></li><li class="listitem">Flash cookies + <p><span class="command"><strong>Design Goal:</strong></span> + +Users should be able to click-to-play flash objects from trusted sites. To +make this behavior unlinkable, we wish to include a settings file for all platforms that disables flash +cookies using the <a class="ulink" href="http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager03.html" target="_top">Flash +settings manager</a>. + </p><p><span class="command"><strong>Implementation Status:</strong></span> + +We are currently <a class="ulink" href="https://trac.torproject.org/projects/tor/ticket/3974" target="_top">having +difficulties</a> causing Flash player to use this settings +file on Windows. + </p></li><li class="listitem">TLS session resumption and HTTP Keep-Alive <p> TLS session resumption and HTTP Keep-Alive MUST NOT allow third party origins @@ -839,11 +852,11 @@ </p></li></ol></div></div><div class="sect2" title="3.7. Long-Term Unlinkability via "New Identity" button"><div class="titlepage"><div><div><h3 class="title"><a id="new-identity"></a>3.7. Long-Term Unlinkability via "New Identity" button</h3></div></div></div><p> In order to avoid long-term linkability, we provide a "New Identity" context menu option in Torbutton. - </p><div class="sect3" title="Design Goal:"><div class="titlepage"><div><div><h4 class="title"><a id="id2751206"></a>Design Goal:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> + </p><div class="sect3" title="Design Goal:"><div class="titlepage"><div><div><h4 class="title"><a id="id2853903"></a>Design Goal:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote">
All linkable identifiers and browser state MUST be cleared by this feature.
- </blockquote></div></div><div class="sect3" title="Implementation Status:"><div class="titlepage"><div><div><h4 class="title"><a id="id2756691"></a>Implementation Status:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> + </blockquote></div></div><div class="sect3" title="Implementation Status:"><div class="titlepage"><div><div><h4 class="title"><a id="id2874701"></a>Implementation Status:</h4></div></div></div><div class="blockquote"><blockquote class="blockquote"> First, Torbutton disables all open tabs and windows via nsIContentPolicy blocking, and then closes each tab and window. The extra step for blocking tabs is done as a precaution to @@ -939,7 +952,7 @@ This patch prevents random URLs from being inserted into content-prefs.sqllite in the profile directory as content prefs change (includes site-zoom and perhaps other site prefs?). - </p></li></ol></div></div></div><div class="sect1" title="4. Packaging"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Packaging"></a>4. Packaging</h2></div></div></div><p> </p><div class="sect2" title="4.1. Build Process Security"><div class="titlepage"><div><div><h3 class="title"><a id="build-security"></a>4.1. Build Process Security</h3></div></div></div><p> </p></div><div class="sect2" title="4.2. External Addons"><div class="titlepage"><div><div><h3 class="title"><a id="addons"></a>4.2. External Addons</h3></div></div></div><p> </p><div class="sect3" title="Included Addons"><div class="titlepage"><div><div><h4 class="title"><a id="id2757442"></a>Included Addons</h4></div></div></div></div><div class="sect3" title="Excluded Addons"><div class="titlepage"><div><div><h4 class="title"><a id="id2782047"></a>Excluded Addons</h4></div></div></div></div><div class="sect3" title="Dangerous Addons"><div class="titlepage"><div><div><h4 cla ss="title"><a id="id2771088"></a>Dangerous Addons</h4></div></div></div></div></div><div class="sect2" title="4.3. Pref Changes"><div class="titlepage"><div><div><h3 class="title"><a id="prefs"></a>4.3. Pref Changes</h3></div></div></div><p> </p></div><div class="sect2" title="4.4. Update Security"><div class="titlepage"><div><div><h3 class="title"><a id="update-mechanism"></a>4.4. Update Security</h3></div></div></div><p> </p></div></div><div class="sect1" title="5. Testing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Testing"></a>5. Testing</h2></div></div></div><p> + </p></li></ol></div></div></div><div class="sect1" title="4. Packaging"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Packaging"></a>4. Packaging</h2></div></div></div><p> </p><div class="sect2" title="4.1. Build Process Security"><div class="titlepage"><div><div><h3 class="title"><a id="build-security"></a>4.1. Build Process Security</h3></div></div></div><p> </p></div><div class="sect2" title="4.2. External Addons"><div class="titlepage"><div><div><h3 class="title"><a id="addons"></a>4.2. External Addons</h3></div></div></div><p> </p><div class="sect3" title="Included Addons"><div class="titlepage"><div><div><h4 class="title"><a id="id2886800"></a>Included Addons</h4></div></div></div></div><div class="sect3" title="Excluded Addons"><div class="titlepage"><div><div><h4 class="title"><a id="id2882777"></a>Excluded Addons</h4></div></div></div></div><div class="sect3" title="Dangerous Addons"><div class="titlepage"><div><div><h4 cla ss="title"><a id="id2864076"></a>Dangerous Addons</h4></div></div></div></div></div><div class="sect2" title="4.3. Pref Changes"><div class="titlepage"><div><div><h3 class="title"><a id="prefs"></a>4.3. Pref Changes</h3></div></div></div><p> </p></div><div class="sect2" title="4.4. Update Security"><div class="titlepage"><div><div><h3 class="title"><a id="update-mechanism"></a>4.4. Update Security</h3></div></div></div><p> </p></div></div><div class="sect1" title="5. Testing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="Testing"></a>5. Testing</h2></div></div></div><p>
The purpose of this section is to cover all the known ways that Tor browser security can be subverted from a penetration testing perspective. The hope