1862395 - Incorrect browser version in user agent when resistFingerprinting is enabled

Status: ASSIGNED

(SeaMonkey :: General, defect)

Description

[supsm2017]

Attachment: Screenshot 2023-11-01 031344.png

Steps to reproduce:

• Enable privacy.resistFingerprinting in about:config
• View user agent in about: or a website

Actual results:

User agent is "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:-1.0) Gecko/20100101 Firefox/-1.0"
Version is incorrectly -1.0. Seamonkey uses a now-incorrect formula to predict the latest ESR release and is possibly getting the incorrect current version number (nsRFPService::GetSpoofedUserAgent in toolkit/components/resistfingerprinting/nsRFPService.cpp).

Expected results:

Firefox version number should be something more sensible. In firefox upstream the user agent version is pretty much hardcoded through the build system.

Comment 1

[Tom Ritter [:tjr]]

I'm not sure what Seamonkey is doing, but we took out the code to try to calculate the ESR version a bit ago...

Comment 2

[supsm2017]

It's still in seamonkey
https://gitlab.com/seamonkey-project/seamonkey-2.53-mozilla/-/blob/2_53_17_1_final/toolkit/components/resistfingerprinting/nsRFPService.cpp?ref_type=heads#L316

Comment 3

[Frank-Rainer Grahl (:frg)]

Has been so for ages. Not really supported so not exposed in the ui either. I will take a look when I find some time.

Comment 5

[Chris Ross]

@Sylvestre Ledru Re: bug 1780833 (duplicate)
Comments that help move issues towards a resolution (like all of this thread) are always welcome.
Comments that falsely pretend that a bug is invalid or resolved (when it is recognised to exist and persist), however, are not.

Comment 6

[Matt A. Tobin [:nsITobin]]

Looking at it I am /reasonably/ able to determine the -1 version is actually correct for the code as written because SeaMonkey's major version is 2 the error is using the Application version and not the platformVersion.

Looks like it was later resolved by preproccessing in a constant based on MOZILLA_UAVERSION. For SeaMonkey it would make more sense to bind it to the Firefox Compatibility Version pref as this would be more useful to users.

Comment 7

[Matt A. Tobin [:nsITobin]]

Attachment: 1862395-incorrect-version-resistfingerprinting.patch

Comment 8

[Matt A. Tobin [:nsITobin]]

Attachment: 1862395-incorrect-version-resistfingerprinting-v2.patch

Simplified with a build var

Comment 9

[Matt A. Tobin [:nsITobin]]

The usefulness of an actual pref to set the compatibility version even for other purposes remains unclear when site-specific user agent overrides is a noted feature thus that can be done in another bug if desired.

Comment 10

[Frank-Rainer Grahl (:frg)]

should be in the next 2.53.20 b1 pre for testing