mikeperry's blog

Tor Browser 4.5 is released

The Tor Browser Team is proud to announce the first stable release in the 4.5 series. This release is available from the Tor Browser Project page and also from our distribution directory.

The 4.5 series provides significant usability, security, and privacy enhancements over the 4.0 series. Because these changes are significant, we will be delaying the automatic update of 4.0 users to the 4.5 series for one week.

Usability Improvements


On the usability front, we've improved the application launch experience for both Windows and Linux users. During install, Windows users are now given the choice to add Tor Browser to the Start Menu/Applications view, which should make it easier to find and launch. This choice is on by default, but can be disabled, and only affects the creation of shortcuts - the actual Tor Browser is still self-contained as a portable app folder. On the Linux side, users now start Tor Browser through a new wrapper that enables launching from the File Manager, the Desktop, or the Applications menu. The same wrapper can also be used from the command line.

We've also simplified the Tor menu (the green onion) and the associated configuration windows. The menu now provides information about the current Tor Circuit in use for a page, and also provides an option to request a new Tor Circuit for a site. Tor Browser is also much better at handling Tor Circuits in general: while a site remains in active use, all associated requests will continue to be performed over the same Tor Circuit. This means that sites should no longer suddenly change languages, behaviors, or log you out while you are using them.


Figure 1: The new Tor Onion Menu


Security Improvements


On the security front, the most exciting news is the new Security Slider. The Security Slider provides user-friendly vulnerability surface reduction - as the security level is increased, browser features that were shown to have a high historical vulnerability count in the iSec Partners hardening study are progressively disabled. This feature is available from the Tor onion menu's "Privacy and Security Settings" choice.


Figure 2: The new Security Slider


Our Windows packages are now signed with a hardware signing token graciously donated by DigiCert. This means that Windows users should no longer be prompted about Tor Browser coming from an unknown source. Additionally, our automatic updates are now individually signed with an offline signing key. In both cases, these signatures can be reproducibly removed, so that builders can continue to verify that the packages they produce match the official build binaries.

The 4.5 series also features a rewrite of the obfs2, obfs3, and ScrambleSuit transports in GoLang, as well as the introduction of the new obfs4 transport. The obfs4 transport provides additional DPI and probing resistance features which prevent automated scanning for Tor bridges. As long as they are not discovered via other mechanisms, fresh obfs4 bridge addresses will work in China today. Additionally, barring new attacks, private obfs4 addresses should continue to work indefinitely.


Privacy Improvements


On the privacy front, the 4.5 series improves on our pre-existing first party isolation implementation to prevent third party tracking. First party isolation provides the property that third party advertisements, like buttons, and "mashup" content that is included on one site will only know about your activity on that site, and will not be able to match it to your activity while you are on any other site. In other words, with first party isolation, Facebook, Twitter, and Google+ can't track you around the entire web using their infamous like buttons.

Specifically, in the 4.5 release, we now ensure that blob: URIs are scoped to the URL bar domain that created them, and the SharedWorker API has been disabled to prevent cross-site and third party communication. We also now make full use of Tor's circuit isolation to ensure that all requests for any third party content included by a site travel down the same Tor Circuit. This isolation also ensures that requests to the same third party site actually use separate Tor Circuits when the URL bar domain is different. This request isolation is enforced even when long-lived "HTTP Keep-Alive" connections are used.

We have also improved our resolution and locale fingerprinting defenses, and we now disable the device sensor and video statistics APIs.

New Search Provider


Our default search provider has also been changed to Disconnect. Disconnect provides private Google search results to Tor users without Captchas or bans.

Full Changelogs


Here is the complete list of changes in the 4.5 series since 4.0:

  • All Platforms
    • Update Tor to 0.2.6.7 with additional patches:
      • Bug 15482: Reset timestamp_dirty each time a SOCKSAuth circuit is used
    • Update NoScript to 2.6.9.22
    • Update HTTPS-Everywhere to 5.0.3
      • Bug 15689: Resume building HTTPS-Everywhere from git tags
    • Update meek to 0.17
    • Include obfs4proxy 0.0.5
      • Use obfs4proxy for obfs2, obfs3, obfs4, and ScrambleSuit bridges
    • Pluggable Transport Dependency Updates:
      • Bug 15265: Switch go.net repo to golang.org/x/net
      • Bug 15448: Use golang 1.4.2 for meek and obs4proxy
    • Update Tor Launcher to 0.2.7.4. Changes since 0.2.7.0.2 in 4.0.8:
      • Bug 11879: Stop bootstrap if Cancel or Open Settings is clicked
      • Bug 13271: Display Bridge Configuration wizard pane before Proxy pane
      • Bug 13576: Don't strip "bridge" from the middle of bridge lines
      • Bug 13983: Directory search path fix for Tor Messanger+TorBirdy
      • Bug 14122: Hide logo if TOR_HIDE_BROWSER_LOGO set
      • Bug 14336: Fix navigation button display issues on some wizard panes
      • Bug 15657: Display the host:port of any connection faiures in bootstrap
      • Bug 15704: Do not enable network if wizard is opened
    • Update Torbutton to 1.9.2.2. Changes since 1.7.0.2 in 4.0.8:
      • Bug 3455: Use SOCKS user+pass to isolate all requests from the same url domain
      • Bug 5698: Use "Tor Browser" branding in "About Tor Browser" dialog
      • Bug 7255: Warn users about maximizing windows
      • Bug 8400: Prompt for restart if disk records are enabled/disabled.
      • Bug 8641: Create browser UI to indicate current tab's Tor circuit IPs
        • (Many Circuit UI issues were fixed during 4.5; see release changelogs for those).
      • Bug 9387: Security Slider 1.0
        • Include descriptions and tooltip hints for security levels
        • Notify users that the security slider exists
        • Make use of new SVG, jar, and MathML prefs
      • Bug 9442: Add New Circuit button to Torbutton menu
      • Bug 9906: Warn users before closing all windows and performing new identity.
      • Bug 10216: Add a pref to disable the local tor control port test
      • Bug 10280: Strings and pref for preventing plugin initialization.
      • Bug 11175: Remove "About Torbutton" from onion menu.
      • Bug 11236: Don't set omnibox order in Torbutton (to prevent translation)
      • Bug 11449: Fix new identity error if NoScript is not enabled
      • Bug 13019: Change locale spoofing pref to boolean
      • Bug 13079: Option to skip control port verification
      • Bug 13406: Stop directing users to download-easy.html.en on update
      • Bug 13650: Clip initial window height to 1000px
      • Bugs 13751+13900: Remove SafeCache cache isolation code in favor of C++ patch
      • Bug 13766: Set a 10 minute circuit lifespan for non-content requests
      • Bug 13835: Option to change default Tor Browser homepage
      • Bug 13998: Handle changes in NoScript 2.6.9.8+
      • Bug 14100: Option to hide NetworkSettings menuitem
      • Bug 14392: Don't steal input focus in about:tor search box
      • Bug 14429: Provide automatic window resizing, but disable for now
      • Bug 14448: Restore Torbutton menu operation on non-English localizations
      • Bug 14490: Use Disconnect search in about:tor search box
      • Bug 14630: Hide Torbutton's proxy settings tab.
      • Bug 14631: Improve profile access error msgs (strings for translation).
      • Bugs 14632+15334: Display Cookie Protections only if disk records are enabled
      • Bug 15085: Fix about:tor RTL text alignment problems
      • Bug 15460: Ensure FTP urls use content-window circuit isolation
      • Bug 15502: Wipe blob: URIs on New Identity
      • Bug 15533: Restore default security level when restoring defaults
      • Bug 15562: Bind SharedWorkers to thirdparty pref
    • Bug 3455: Patch Firefox SOCKS and proxy filters to allow user+pass isolation
    • Bug 4100: Raise HTTP Keep-Alive back to 115 second default
    • Bug 5698: Fix branding in "About Torbrowser" window
    • Bug 10280: Don't load any plugins into the address space by default
    • Bug 11236: Fix omnibox order for non-English builds
      • Also remove Amazon, eBay and bing; add Youtube and Twitter
    • Bug 11955: Backport HTTPS Certificate Pinning patches from Firefox 32
    • Bug 12430: Provide a preference to disable remote jar: urls
    • Bugs 12827+15794: Create preference to disable SVG images (for security slider)
    • Bug 13019: Prevent Javascript from leaking system locale
    • Bug 13379: Sign our MAR update files
    • Bug 13439: No canvas prompt for content callers
    • Bug 13548: Create preference to disable MathML (for security slider)
    • Bug 13586: Make meek use TLS session tickets (to look like stock Firefox).
    • Bug 13684: Backport Mozilla bug #1066190 (pinning issue fixed in Firefox 33)
    • Bug 13788: Fix broken meek in 4.5-alpha series
    • Bug 13875: Spoof window.devicePixelRatio to avoid DPI fingerprinting
    • Bug 13900: Remove 3rd party HTTP auth tokens via Firefox patch
    • Bug 14392: Make about:tor hide itself from the URL bar
    • Bug 14490: Make Disconnect the default omnibox search engine
    • Bug 14631: Improve startup error messages for filesystem permissions issues
    • Bugs 14716+13254: Fix issues with HTTP Auth usage and TLS connection info display
    • Bug 14937: Hard-code meek and flashproxy node fingerprints
    • Bug 15029: Don't prompt to include missing plugins
    • Bug 15406: Only include addons in incremental updates if they actually update
    • Bug 15411: Remove old (and unused) cacheDomain cache isolation mechanism
    • Bug 15502: Isolate blob: URI scope to URL domain; block WebWorker access
    • Bug 15562: Disable Javascript SharedWorkers due to third party tracking
    • Bug 15757: Disable Mozilla video statistics API extensions
    • Bug 15758: Disable Device Sensor APIs
  • Linux
    • Bug 12468: Only print/write log messages if launched with --debug
    • Bug 13375: Create a hybrid GUI/desktop/shell launcher wrapper
    • Bug 13717: Make sure we use the bash shell on Linux
    • Bug 15672: Provide desktop app registration+unregistration for Linux
    • Bug 15747: Improve start-tor-browser argument handling
  • Windows
    • Bug 3861: Begin signing Tor Browser for Windows the Windows way
    • Bug 10761: Fix instances of shutdown crashes
    • Bug 13169: Don't use /dev/random on Windows for SSP
    • Bug 14688: Create shortcuts to desktop and start menu by default (optional)
    • Bug 15201: Disable 'runas Administrator' codepaths in updater
    • Bug 15539: Make installer exe signatures reproducibly removable
  • Mac
    • Bug 10138: Switch to 64bit builds for MacOS



Here is the list of changes since the last 4.5 alpha (4.5a5):

  • All Platforms
    • Update Tor to 0.2.6.7 with additional patches:
      • Bug 15482: Reset timestamp_dirty each time a SOCKSAuth circuit is used
    • Update NoScript to 2.6.9.22
    • Update HTTPS-Everywhere to 5.0.3
      • Bug 15689: Resume building HTTPS-Everywhere from git tags
    • Update meek to 0.17
    • Update obfs4proxy to 0.0.5
    • Update Tor Launcher to 0.2.7.4
      • Bug 15704: Do not enable network if wizard is opened
      • Bug 11879: Stop bootstrap if Cancel or Open Settings is clicked
      • Bug 13576: Don't strip "bridge" from the middle of bridge lines
      • Bug 15657: Display the host:port of any connection faiures in bootstrap
    • Update Torbutton to 1.9.2.2
      • Bug 15562: Bind SharedWorkers to thirdparty pref
      • Bug 15533: Restore default security level when restoring defaults
      • Bug 15510: Close Tor Circuit UI control port connections on New Identity
      • Bug 15472: Make node text black in circuit status UI
      • Bug 15502: Wipe blob URIs on New Identity
      • Bug 15795: Some security slider prefs do not trigger custom checkbox
      • Bug 14429: Disable automatic window resizing for now
    • Bug 4100: Raise HTTP Keep-Alive back to 115 second default
    • Bug 13875: Spoof window.devicePixelRatio to avoid DPI fingerprinting
    • Bug 15411: Remove old (and unused) cacheDomain cache isolation mechanism
    • Bugs 14716+13254: Fix issues with HTTP Auth usage and TLS connection info display
    • Bug 15502: Isolate blob URI scope to URL domain; block WebWorker access
    • Bug 15794: Crash on some pages with SVG images if SVG is disabled
    • Bug 15562: Disable Javascript SharedWorkers due to third party tracking
    • Bug 15757: Disable Mozilla video statistics API extensions
    • Bug 15758: Disable Device Sensor APIs
  • Linux
    • Bug 15747: Improve start-tor-browser argument handling
    • Bug 15672: Provide desktop app registration+unregistration for Linux
  • Windows
    • Bug 15539: Make installer exe signatures reproducibly removable
    • Bug 10761: Fix instances of shutdown crashes


Post update 4/28/2015: Provide screenshots of the Tor Onion menu and Security Slider.
Post update 4/28/2015: Add section headers.

Tor Browser 4.0.8 is released

A new release for the stable Tor Browser is available from the Tor Browser Project page and also from our distribution directory.

This release contains a fix for the update loop issue present in 4.0.7. It is otherwise identical to that release.

Both 4.0.7 and 4.0.8 contain an update to the included Tor software, to fix two crash bugs in the version of the Tor software included prior to 4.0.7. One crash bug affects only people using the bundled tor binary to run hidden services, and the other crash bug allows a malicious website or Tor exit node to crash the underlying tor client by inducing it to load a resource from a hidden service with a malformed descriptor. These bugs do not allow remote code execution, but because they can be used by arbitrary actors to perform a denial of service, we are issuing a security update to address them.

There will be no corresponding 4.5-alpha release for this fix, to allow us to focus on stabilizing that series for release in ~2 weeks.

Note to MacOS users: This is the last planned release that will run on 32 bit MacOS versions. Users of Mac OS 10.8 (Mountain Lion) and newer versions will be automatically updated to the 64 bit Tor Browser 4.5 when it is stabilized in April, and we expect this transition to be smooth for those users. However, the update process for 10.6 and 10.7 users will unfortunately not be automatic. For more details, see the original end-of-life blog post.

Here is the complete changelog since 4.0.6 (covering 4.0.7 and 4.0.8):

  • All Platforms
    • Bug 15637: Fix update loop due to improper versioning
    • Update Tor to 0.2.5.12
    • Update NoScript to 2.6.9.21

Tor Browser 4.0.7 is released

Unfortunately, the 4.0.7 release has a bug that makes it think of itself as 4.0.6, causing an update loop. This version mismatch will also cause the incremental update to 4.0.8 to fail to properly apply. The browser will then download the full update at that point, which should succeed, but at the expense of both user delay and wasted Tor network bandwidth.

For this reason, we have decided to pull 4.0.7 from the website at the moment, and instead prepare 4.0.8 as soon as possible.

Thank you for your patience.

Tor Browser 4.5a5 is released

The Tor Browser team is proud to announce the release of the fifth alpha of the 4.5 series of Tor Browser. The release is available from the extended downloads page and also from our distribution directory.

Tor Browser 4.5a5 is based on Firefox ESR 31.6.0, which features important security updates to Firefox.

We're very excited about the usability and security improvements in this release. On the usability front, we've created a FreeDesktop-compatible launcher wrapper for Linux that can be invoked from either the GUI or the shell, and we also provide Windows users with the ability to add optional Start Menu and Desktop shortcuts. The circuit usage of Tor Browser has also been improved to avoid transitioning to a new circuit for a website while it is in active use.

On the security front, the Security Slider now has full descriptions of the browser behaviors that are changed at each security level. We've also made improvements to our display resolution fingerprinting defenses to automatically resize the browser window to a 200x100 pixel multiple after resize or maximization, and to perform similar resizing for full screen HTML5 video. Finally, the Windows releases are also now signed using the hardware signing token graciously provided to us by DigiCert, so Windows users should no longer be warned about Tor Browser being downloaded from an "unknown publisher".

And those are just the highlights. The complete list of changes since the 4.5a4 release is as follows:

  • All Platforms
    • Update Firefox to 31.6.0esr
    • Update OpenSSL to 1.0.1m
    • Update Tor to 0.2.6.6
    • Update NoScript to 2.6.9.19
    • Update HTTPS-Everywhere to 5.0
    • Update meek to 0.16
    • Update Tor Launcher to 0.2.7.3
      • Bug 13983: Directory search path fix for Tor Messanger+TorBirdy
    • Update Torbutton to 1.9.1.0
      • Bug 9387: "Security Slider 1.0"
        • Include descriptions and tooltip hints for security levels
        • Notify users that the security slider exists
        • Flip slider so that "low" is on the bottom
        • Make use of new SVG and MathML prefs
      • Bug 13766: Set a 10 minute circuit lifespan for non-content requests
      • Bug 15460: Ensure FTP urls use content-window circuit isolation
      • Bug 13650: Clip initial window height to 1000px
      • Bug 14429: Ensure windows can only be resized to 200x100px multiples
      • Bug 15334: Display Cookie Protections menu if disk records are enabled
      • Bug 14324: Show HS circuit in Tor circuit display
      • Bug 15086: Handle RTL text in Tor circuit display
      • Bug 15085: Fix about:tor RTL text alignment problems
      • Bug 10216: Add a pref to disable the local tor control port test
      • Bug 14937: Show meek and flashproxy bridges in tor circuit display
      • Bugs 13891+15207: Fix exceptions/errors in circuit display with bridges
      • Bug 13019: Change locale hiding pref to boolean
      • Bug 7255: Warn users about maximizing windows
      • Bug 14631: Improve profile access error msgs (strings).
    • Pluggable Transport Dependency Updates:
      • Bug 15448: Use golang 1.4.2 for meek and obs4proxy
      • Bug 15265: Switch go.net repo to golang.org/x/net
    • Bug 14937: Hard-code meek and flashproxy node fingerprints
    • Bug 13019: Prevent Javascript from leaking system locale
    • Bug 10280: Improved fix to prevent loading plugins into address space
    • Bug 15406: Only include addons in incremental updates if they actually update
    • Bug 15029: Don't prompt to include missing plugins
    • Bug 12827: Create preference to disable SVG images (for security slider)
    • Bug 13548: Create preference to disable MathML (for security slider)
    • Bug 14631: Improve startup error messages for filesystem permissions issues
    • Bug 15482: Don't allow circuits to change while a site is in use
  • Linux
    • Bug 13375: Create a hybrid GUI/desktop/shell launcher wrapper
    • Bug 12468: Only print/write log messages if launched with --debug
  • Windows
    • Bug 3861: Begin signing Tor Browser for Windows the Windows way
    • Bug 15201: Disable 'runas Administrator' codepaths in updater
    • Bug 14688: Create shortcuts to desktop and start menu by default (optional)

Tor Browser 4.0.6 is released

A new release for the stable Tor Browser is available from the Tor Browser Project page and also from our distribution directory.

Tor Browser 4.0.6 is based on Firefox ESR 31.6.0, which features important security updates to Firefox.

Note to MacOS users: This is the last planned release that will run on 32 bit MacOS versions. Users of Mac OS 10.8 (Mountain Lion) and newer versions will be automatically updated to the 64 bit Tor Browser 4.5 when it is stabilized in April, and we expect this transition to be smooth for those users. However, the update process for 10.6 and 10.7 users will unfortunately not be automatic. For more details, see the original end-of-life blog post.

Here is the complete changelog since 4.0.5:

  • All Platforms
    • Update Firefox to 31.6.0esr
    • Update meek to 0.16
    • Update OpenSSL to 1.0.1m

Tor Browser 4.0.4 is released

A new release for the stable Tor Browser is available from the Tor Browser Project page and also from our distribution directory.

Note: The individual bundles of the stable series are signed by one of the subkeys of the Tor Browser Developers signing key from now on, too. You can find its fingerprint on the Signing Keys page. It is:

pub   4096R/0x4E2C6E8793298290 2014-12-15
      Key fingerprint = EF6E 286D DA85 EA2A 4BA7
                        DE68 4E2C 6E87 9329 8290


Tor Browser 4.0.4 is based on Firefox ESR 31.5.0, which features important security updates to Firefox. Additionally, it contains updates to NoScript, HTTPS-Everywhere, and OpenSSL (none of the OpenSSL advisories since OpenSSL 1.0.1i have affected Tor, but we decided to update to the latest 1.0.1 release anyway).

Here is the changelog since 4.0.3:

  • All Platforms
    • Update Firefox to 31.5.0esr
    • Update OpenSSL to 1.0.1l
    • Update NoScript to 2.6.9.15
    • Update HTTPS-Everywhere to 4.0.3
    • Bug 14203: Prevent meek from displaying an extra update notification
    • Bug 14849: Remove new NoScript menu option to make permissions permanent
    • Bug 14851: Set NoScript pref to disable permanent permissions

Tor Browser 4.5a4 is released

The Tor Browser team is proud to announce the release of the fourth alpha of the 4.5 series of Tor Browser. The release is available from the extended downloads page and also from our distribution directory.

Tor Browser 4.5a4 is based on Firefox ESR 31.5.0, which features important security updates to Firefox. Moreover, this release includes an updated Tor, 0.2.6.3-alpha, and switches Scramblesuit and obfs3 bridge support to a new golang-based implementation. We are especially interested in hearing any issues with using obfs3, obfs4, and Scramblesuit in this release.

The release also features several improvements to usability, following the results of the usability sprint at the end of last month. In particular, the Torbutton onion menu and related preference windows have been overhauled to provide more simplicity and more focus. The onion menu now features a much requested "New Circuit for this site" option, and the security and privacy settings window have been simplified. For censored users, the first run configuration wizard was also improved to present the choice of Pluggable Transport before the local proxy information, in an effort to avoid confusion between Pluggable Transports and local proxies. As can be seen from the changelog below, the release contains several other usability tweaks and enhancements as well.

Here is the full changelog for changes since 4.5-alpha-3:

  • All Platforms
    • Update Firefox to 31.5.0esr
    • Update Tor to 0.2.6.3-alpha
    • Update OpenSSL to 1.0.1l
    • Update NoScript to 2.6.9.15
    • Update obfs4proxy to 0.0.4
      • Use obfs4proxy for ScrambleSuit bridges
    • Update Torbutton to 1.9.0.0
      • Bug 13882: Fix display of bridges after bridge settings have been changed
      • Bug 5698: Use "Tor Browser" branding in "About Tor Browser" dialog
      • Bug 10280: Strings and pref for preventing plugin initialization.
      • Bug 14866: Show correct circuit when more than one exists for a given domain
      • Bug 9442: Add New Circuit button to Torbutton menu
      • Bug 9906: Warn users before closing all windows and performing new identity.
      • Bug 8400: Prompt for restart if disk records are enabled/disabled.
      • Bug 14630: Hide Torbutton's proxy settings tab.
      • Bug 14632: Disable Cookie Manager until we get it working.
      • Bug 11175: Remove "About Torbutton" from onion menu.
      • Bug 13900: Remove remaining SafeCache code in favor of C++ patch
      • Bug 14490: Use Disconnect search in about:tor search box
      • Bug 14392: Don't steal input focus in about:tor search box
      • Bug 11236: Don't set omnibox order in Torbutton (to prevent translation)
      • Bug 13406: Stop directing users to download-easy.html.en on update
      • Bug 9387: Handle "custom" mode better in Security Slider
      • Bug 12430: Bind jar: pref to Security Slider
      • Bug 14448: Restore Torbutton menu operation on non-English localizations
      • Translation updates
    • Update Tor Launcher to 0.2.7.2
      • Bug 13271: Display Bridge Configuration wizard pane before Proxy pane
      • Bug 14336: Fix navigation button display issues on some wizard panes
      • Translation updates
    • Bug 14203: Prevent meek from displaying an extra update notification
    • Bug 14849: Remove new NoScript menu option to make permissions permanent
    • Bug 14851: Set NoScript pref to disable permanent permissions
    • Bug 14490: Make Disconnect the default omnibox search engine
    • Bug 11236: Fix omnibox order for non-English builds
      • Also remove Amazon, eBay and bing; add Youtube and Twitter
    • Bug 10280: Don't load any plugins into the address space.
    • Bug 14392: Make about:tor hide itself from the URL bar
    • Bug 12430: Provide a preference to disable remote jar: urls
    • Bug 13900: Remove 3rd party HTTP auth tokens via Firefox patch
    • Bug 5698: Fix branding in "About Torbrowser" window
  • Windows:
    • Bug 13169: Don't use /dev/random on Windows for SSP
  • Linux:
    • Bug 13717: Make sure we use the bash shell on Linux

Note: Once again, the individual bundles of both Tor Browser series are signed by one of the subkeys of the Tor Browser Developers signing key from now on. You can find its fingerprint on the Signing Keys page. It is:

pub   4096R/0x4E2C6E8793298290 2014-12-15
      Key fingerprint = EF6E 286D DA85 EA2A 4BA7
                        DE68 4E2C 6E87 9329 8290

Tor Browser 4.5-alpha-1 is released

The first alpha release of the 4.5 series is available from the extended downloads page and also from our distribution directory.

This release features a circuit status reporting UI (visible on the green Tor onion button menu), as well as isolation for circuit use. All content elements for a website will use a single circuit, and different websites should use different circuits, even when viewed at the same time. The Security Slider is also present in this release, and can be configured from the green Tor onion's Preferences menu, under the Privacy and Security settings tab. It also features HTTPS certificate pinning for selected sites (including our updater), which was backported from Firefox 32.

This release also features a rewrite of the obfs3 pluggable transport, and the introduction of the new obfs4 transport. Please test these transports and report any issues!

Note to Mac users: As part of our planned end-of-life for supporting 32 bit Macs, the Mac edition of this release is 64 bit only, which also means that the updater will not work for Mac users on the alpha series release channel for this release. Once you transition to this 64 bit release, the updater should function correctly after that.

Here is the complete changelog since 4.0.1:

  • All Platforms
    • Bug 3455: Patch Firefox SOCKS and proxy filters to allow user+pass isolation
    • Bug 11955: Backport HTTPS Certificate Pinning patches from Firefox 32
    • Bug 13684: Backport Mozilla bug #1066190 (pinning issue fixed in Firefox 33)
    • Bug 13019: Make JS engine use English locale if a pref is set by Torbutton
    • Bug 13301: Prevent extensions incompatibility error after upgrades
    • Bug 13460: Fix MSVC compilation issue
    • Bug 13504: Remove stale bridges from default bridge set
    • Bug 13742: Fix domain isolation for content cache and disk-enabled browsing mode
    • Update Tor to 0.2.6.1-alpha
    • Update NoScript to 2.6.9.3
    • Bug 13586: Make meek use TLS session tickets (to look like stock Firefox).
    • Bug 12903: Include obfs4proxy pluggable transport
    • Update Torbutton to 1.8.1.1
      • Bug 9387: Provide a "Security Slider" for vulnerability surface reduction
      • Bug 13019: Synchronize locale spoofing pref with our Firefox patch
      • Bug 3455: Use SOCKS user+pass to isolate all requests from the same url domain
      • Bug 8641: Create browser UI to indicate current tab's Tor circuit IPs
      • Bug 13651: Prevent circuit-status related UI hang.
      • Bug 13666: Various circuit status UI fixes
      • Bug 13742+13751: Remove cache isolation code in favor of direct C++ patch
      • Bug 13746: Properly update third party isolation pref if disabled from UI
  • Windows
    • Bug 13443: Re-enable DirectShow; fix crash with mingw patch.
    • Bug 13558: Fix crash on Windows XP during download folder changing
    • Bug 13091: Make app name "Tor Browser" instead of "Tor"
    • Bug 13594: Fix update failure for Windows XP users
  • Mac
    • Bug 10138: Switch to 64bit builds for MacOS
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