SecBrowser ™ in Microsoft Windows: A Security-hardened, Non-anonymous Browser
- 1 Introduction
- 2 Security Enhancements
- 3 Privacy and Fingerprinting Resistance
- 4 SecBrowser Installation
- 5 Source Tor Browser
- 6 SecBrowser ™ Configuration
- 7 Normalizing SecBrowser ™ Behavior
- 8 Non-Affiliation with The Tor Project
- 9 Footnotes
SecBrowser ™ is a derivative of the Tor Browser Bundle (which itself is a derivative of Mozilla Firefox) but without Tor. This means unlike Tor Browser, SecBrowser ™ does not route traffic over the Tor network, which in common parlance is referred to as "clearnet" traffic. Even without the aid of the Tor network, SecBrowser ™ still benefits from the numerous patches [archive] that Tor developers have merged into the code base. Even with developer skills, these enhancements would be arduous and time-consuming to duplicate in other browsers, with the outcome unlikely to match SecBrowser's ™ many security benefits. While browser extensions can be installed to mitigate specific attack vectors, this ad hoc approach is insufficient. SecBrowser ™ leverages the experience and knowledge of skilled Tor Project developers, and the battle-tested Tor Browser.
Table: SecBrowser ™ Security and Privacy Benefits
|Security Slider||Enables improved security by disabling certain web features that can be used as attack vectors.|
|Default Tor Browser Add-ons||
|Firejail (Linux only)||Firejail will be used as a sandboxing measure to restrict the SecBrowser process. |
|Homograph Attack Protection||Fixes the internationalized domain name (IDN) homograph attack vulnerability [archive] present in standard Firefox and Tor Browser releases.  |
|Reproducible Builds||Build security is achieved through a reproducible build process that enables anyone to produce byte-for-byte identical binaries to the ones the Tor Project releases.|
|WebRTC Disabled by Default||WebRTC can compromise the security of VPN tunnels, by exposing the external (real) IP address of a user.|
Privacy and Fingerprinting Resistance
Research from a pool of 500,000 Internet users has shown that the vast majority (84%) have unique browser configurations and version information which makes them trackable across the Internet. When Java or Flash is installed, this figures rises to 94%. SecBrowser ™ shares the fingerprint with around three million [archive] other Tor Browser users, which allows people who use SecBrowser ™ to "blend in" with the larger population and better protect their privacy.
- Use of Torbutton, which is bundled with SecBrowser ™ and enabled by default.
- Use of mobile devices like Android and iPhone.
- Corporate desktop machines which are clones of one another.
- The User Agent is uniform for all Torbutton users.
- Plugins are blocked.
- The screen resolution is rounded down to 50 pixel multiples.
- The timezone is set to GMT.
- DOM Storage is cleared and disabled.
Note: Because tracking techniques are complex, Panopticlick does not measure all forms of tracking and protection.
- SecBrowser ™ conveys 6.26 bits of identifying information.
- One in 76.46 browsers have the same fingerprint.
- Browsers that convey lower bits of identification are better at resisting fingerprinting.
Table: Tor Browser vs SecBrowser ™ HTTP headers comparison.
Percentage (%) out of 1652 with fingerprints tags [Firefox,Windows]:
|User-Agent||Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Firefox/60.0||2.48||2.42|
|Accepting-Encoding||gzip, deflate, br||82.14||82.13|
The following guide provides steps to:
- Source Tor Browser
- Install Tor Browser
- Disable Tor
- Start Tor Browser
- Normalize SecBrowser ™ Behavior
Source Tor Browser
Download Tor Browser Installer for Windows
Install Tor Browser
SecBrowser ™ Configuration
Start Tor Browser
Tor Browser can be started by launching the
Start TB without Tor.bat batch file.
If configured correctly Tor Browser will have a red background with a message stating "Something Went Wrong!" Tor is not working in this browser.
Figure: Tor Browser "Something Went Wrong"
Normalizing SecBrowser ™ Behavior
Usability vs. Security
While SecBrowser ™ has numerous security enhancements they can come at a cost of decreased usability. Since it is also highly configurable, security settings and behavior can be customized according to personal requirements. This is commonly referred to as an usability vs. security trade-off.
Tor Browser behavior can be modified by creating a
user.js file in the Tor Browser default.profile folder. Users can then add custom settings to meet usability requirements.
SecBrowser ™ has a “Security Slider” in the shield menu. This can increase security by disabling certain web features that pose possible attack vectors. By default, the Tor Browser Security Slider is set to “Standard” which is the lowest security level. Conversely the SecBrowser ™ security level is set to "Safest" which will prevent some web pages from functioning properly, so security needs must be weighed against the degree of usability that is required. Users can adjust the security slider as needed to meet usability / security requirements.
Private Browsing Mode
In the default configuration Tor Browser has private browsing mode enabled. This setting prevents browsing and download history as well as cookies from remaining persistent across SecBrowser ™ restarts. However, private browsing mode can be disabled by setting
browser.privatebrowsing.autostart to "false".
When private browsing mode is disabled, SecBrowser ™'s built-in "long-term linkability" protections are deactivated. This means users are vulnerable to attacks which can link activities between earlier and later browsing sessions. If privacy is paramount users can enable private browsing mode by commenting out the corresponding user preference.
Persistent NoScript Settings
NoScript settings can be set to persist across browser restarts by setting
extensions.torbutton.noscript_persist to "true". This is a security vs usability trade-off. If the SecBrowser ™ “Security Slider” setting is changed afterwards, all NoScript preferences are overridden and all custom, per-site settings are lost. This holds true regardless of whether the security setting was increased or decreased.
Remember Logins and Passwords for Sites
By default, Tor Browser does not save site login information such as user names or passwords. To save login information users can set
signon.rememberSignons to "true", which allows user names and passwords to be saved across browser sessions.
If a user disables some of Tor Browser's own anti-tracking features (like private browsing mode; see above), then it is logical to install one or more extensions that make it harder to track later browsing. The extensions Disconnect [archive], Privacy Badger [archive]  and uBlock Origin [archive] are all open-source and are generally recommended. Research which one(s) are most suitable in your circumstances; their use cases are different.
Non-Affiliation with The Tor Project
SecBrowser ™ is a derivative of Tor® Browser, produced independently from the Tor® anonymity software and carries no guarantee from The Tor® Project [archive] about quality, suitability or anything else.
- https://2019.www.torproject.org/projects/torbrowser/design/ [archive]
- https://tb-manual.torproject.org/security-slider/ [archive]
- https://www.eff.org/https-everywhere [archive]
- https://en.wikipedia.org/wiki/NoScript [archive]
- https://forums.whonix.org/t/automatically-firejailing-tor-browser/4767 [archive]
- For further information, see: very hard to notice Phishing Scam - Firefox / Tor Browser URL not showing real Domain Name - Homograph attack (Punycode) [archive]. Without this change, URLs can be spoofed so users are deceived about what remote server they are communicating with, via substitution of characters that look alike ('homographs').
- https://bugzilla.mozilla.org/show_bug.cgi?id=1332714 [archive]
- https://2019.www.torproject.org/projects/torbrowser/design/ [archive]
- https://blog.torproject.org/deterministic-builds-part-two-technical-details [archive]
- https://en.wikipedia.org/wiki/WebRTC#Concerns [archive]
- https://torrentfreak.com/huge-security-flaw-leaks-vpn-users-real-ip-addresses-150130/ [archive]
- https://www.eff.org/deeplinks/2010/05/every-browser-unique-results-fom-panopticlick [archive]
- https://blog.torproject.org/effs-panopticlick-and-torbutton [archive]
- https://33bits.wordpress.com/about/ [archive]
- It is necessary to set the
SET TOR_SKIP_LAUNCH=1environment variable, then start Tor Browser. The Tor Browser Launcher add-on will detect this, skip the connection wizard and skip launching Tor.
- https://forums.whonix.org/t/disable-tor-in-torbrowser-9/8336 [archive]
- The browser might need to be restarted for it to work.
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