1487842 - Remove weak TLS_DHE_RSA_* ciphers from Firefox for Android

Status: RESOLVED INCOMPLETE

(Firefox for Android Graveyard :: Android Sync, enhancement)

Description

[Nick Alexander :nalexander [he/him]]

Per https://groups.google.com/d/msg/mozilla.dev.platform/XyQo24IO0oA/h5bfCqShAwAJ, Firefox (Gecko) will drop the ciphers
    - TLS_DHE_RSA_WITH_AES_128_CBC_SHA
    - TLS_DHE_RSA_WITH_AES_256_CBC_SHA
because they are considered too weak.

For historical reasons Firefox for Android will handshake to Firefox Sync servers using these suites:

https://searchfox.org/mozilla-central/rev/05d91d3e02a0780f44599371005591d7988e2809/mobile/android/services/src/main/java/org/mozilla/gecko/background/common/GlobalConstants.java#73

After discussion off-list, I confirmed that we should drop those suites from Firefox for Android.

Comment 1

[Nick Alexander :nalexander [he/him]]

bobm:

a) can you confirm these cipher suites aren't required for Sync 1.5?  (I'd be shocked if they're in our current AWS configuration, but I've been shocked before.)

b) can you confirm that we can also drop some old versions of TLS/SSLv3 from 

https://searchfox.org/mozilla-central/rev/05d91d3e02a0780f44599371005591d7988e2809/mobile/android/services/src/main/java/org/mozilla/gecko/background/common/GlobalConstants.java#94

c) are you aware of cipher suites requirements coming from SBrowser's use of Firefox Sync?  (I'm not sure this is relevant any more.)

Comment 2

[Bob Micheletto [:bobm]]

(In reply to Nick Alexander :nalexander [he/him] from comment #1)

> a) can you confirm these cipher suites aren't required for Sync 1.5?  (I'd
> be shocked if they're in our current AWS configuration, but I've been
> shocked before.)

In large sample (2/3 of sync traffic for a month) there are no CBC ciphers present.  Which isn't surprising since they aren't in the allowed ciphers list configuration.

> b) can you confirm that we can also drop some old versions of TLS/SSLv3 from 
> 
> https://searchfox.org/mozilla-central/rev/
> 05d91d3e02a0780f44599371005591d7988e2809/mobile/android/services/src/main/
> java/org/mozilla/gecko/background/common/GlobalConstants.java#94

0.05 percent of Sync traffic uses TLSv1.  Most of that is from SBrowser:
Firefox AndroidSync 1.@MOZ_APP_VERSION@.0 (Firefox) TLSv1 DHE-RSA-AES256-SHA

SSLv3 traffic accounts for .00002% of Sync traffic.

> c) are you aware of cipher suites requirements coming from SBrowser's use of
> Firefox Sync?  (I'm not sure this is relevant any more.)

0.03%     Firefox AndroidSync 1.@MOZ_APP_VERSION@.0 (Firefox) TLSv1 DHE-RSA-AES256-SHA
0.000015% Firefox AndroidSync 1.40.0 (SBrowser) TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384
0.26%     Firefox AndroidSync 1.40.0 (SBrowser) TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256

I'll share you a copy of the collated information I used to answer these questions, in case you'd like to do further investigation.

Comment 3

[BMO Automation]

We have completed our launch of our new Firefox on Android. The development of the new versions use GitHub for issue tracking. If the bug report still reproduces in a current version of [Firefox on Android nightly](https://play.google.com/store/apps/details?id=org.mozilla.fenix) an issue can be reported at the [Fenix GitHub project](https://github.com/mozilla-mobile/fenix/). If you want to discuss your report please use [Mozilla's chat](https://wiki.mozilla.org/Matrix#Connect_to_Matrix) server https://chat.mozilla.org and join the [#fenix](https://chat.mozilla.org/#/room/#fenix:mozilla.org) channel.