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Table of Contents
Spyzilla
Mozilla products by default send some information to NSA. This guide will show you how to change these settings to other secret service of your choice or how to turn them off completely.
See also list of other applications that do not respect privacy.
Client certificates
Check Advanced → Certificates → Ask me every time, we really don't want to authenticate to the remote server automatically! Exploited in the wild!
Firefox
This applies to Firefox <57. We have downloaded Firefox 57, started it, left it for ~30 minutes and were amazed:
- Run with parameter -P. Select “Start offline”
- Visit Preferences. In “Security”, turn off “Block reported attack sites” and “Block reported web forgeries”
- Uncheck Advanced → Updates
- Uncheck Advanced → Certificates → Validation → OCSP (of course this disables fetching certificate revocation info - be sure you know what are you doing)
- Visit about:config. Set extensions.blocklist.enabled = false.
- Search for “http”. Change all URLs to nsalitomerice.cz, localhost or other secret service of your choice.
- Unfortunately, Firefox will still download favicons from Google, Yahoo and Mibbit (incl. cookies) when browsing Preferences in a certain way. Bugreport pending.
- Related: about:addons loads Google Analytics
- If you want to test this with an intercepting proxy, make sure you have security.cert_pinning.enforcement_level 0 or 1
- Disable automatic resolving of local names and URL-like patters: set browser.fixup.alternate.enabled and keyword.enabled to false. PT
- Since version 33, some plugins seem to be downloaded automatically. Set media.gmp-gmpopenh264.autoupdate = false.
- Since version 38, it is not possible to turn this feature off. Additionally, the downloaded binary contained a buffer overflow.
- media.gmp-gmpopenh264.enabled does not help and media.gmp-gmpopenh264.autoupdate does note exist anymore. Try setting media.gmp-manager.lastCheck to the future and media.gmp-manager.url to some non-existent URL.
- Since version 38 (on Windows), a DRM backdoor from Adobe is downloaded automatically: The CDM will be downloaded from Adobe shortly after you upgrade or install Firefox and will be activated when you first interact with a site that uses Adobe CDM.
- This will be fixed in version 52.
- However, in version 57, another DRM backdoor is downloaded on all platforms. How to disable.
- Every time you open new window, Firefox posts your system information to Mozilla, e.g. this one. This can be avoided by aforementioned URL settings or by setting homepage to about:blank.
- Yes, we have API for manipulating browser history. I have no idea if something interesting can be done with it. See browser.history.allow* in about:config.
- Setting this to False breaks webpages, known problems are with zbozi.cz and mapy.cz.
- devtools.gcli.jquerySrc = https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js
- devtools.gcli.lodashSrc = https://cdnjs.cloudflare.com/ajax/libs/lodash.js/2.4.1/lodash.min.js
- devtools.gcli.underscoreSrc = https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.7.0/underscore-min.js
- Files in local filesystem can read files in current directory and post them to a remote server.
- Download this image to your home directory and open it in Firefox.
- HSTS settings cannot be overriden (the decision can be hand-deleted from SiteSecurityServiceState.txt when Firefox is not running (otherwise the file is immediately overwritten), however, if the page sends further broken HSTS headers, subsequent requests will fail anyway). This is in compliance with RFC 6797, section 12.1. NSA Litoměřice believes that this is one of RFCs that are badly designed and should be ignored (the other being e.g. RFC 826, which we describe here)
- You can override it by adding test.currentTimeOffsetSeconds (integer) = 11491200
- And in Chrome, you can override it by typing “badidea” on the error page
- or “thisisunsafe” in newer (2018-03) versions of Chrome
- Neither it seems to be possible to override revoked certificate
- The webpage can detect that element inspector is opened. This should be possible to disable too…
- Recommended: network.IDN_show_punycode = true (more info)
- Firefox 52 ESR downloads browser.safebrowsing.provider.mozilla.gethashURL even if safe browsing is turned off in Preferences
- Some webpages are blocking pasting of password for “better security”, so you cannot use a password manager. Set dom.event.clipboardevents.enabled=false to disable this. This may also mitigate some attacks with clipboard leaking, or replacing content of clipboard with a malicious command
See: Firefox hardening
See also this guide. I have downloaded it from an onion service and put it here for those who don't have access to the darknet.
To be investigated:
Thunderbird
New Account setup wizard sends your e-mail domain to Mozilla. To add an account without this feature, select File → Offline → Work offline.
Firefox for Android
Checks for updates even when the main app is not running. Same as described here.
This update checking does not respect network.proxy.http settings, but connect straight to the network, i.e., a standard intercepting proxy setup won't see it, it won't go through Tor etc.