oss-sec mailing list archives

Re: with firefox on X11, any page can pastejack you anytime


From: Turistu <turistu () gmail com>
Date: Fri, 20 Oct 2023 02:10:06 +0300

On Tue, Oct 17, 2023 at 03:17:36AM +0300, turistu wrote:
In firefox running on X11, any script from any page can freely write to the
primary selection, and that can be easily exploited to run arbitrary code
on the user's machine.

OK this was probably too technical and terse for people not familiar
with X11 programming and terminology, so thing goes like this:

1. If you're a user who has first learned to use a GUI on e.g. Windows,
and who is used to copy & paste with Ctrl-C Ctrl-V (or with left-click,
choose Copy from the menu, and then again left-click, choose Paste),
then congratulations! this DOES NOT AFFECT YOU.

(Unless you're using some clipboard tools which merges the primary and
clipboard selection, but I guess you don't ;-))

2. But if you're a *native* X11 user who is used to just select the text and
then paste it with a middle-click or shift-Insert, then this means you're
pretty much done, and you should immediately either stop using firefox or
try the workaround and patch described in my report. This also includes
Wayland users.

I have no idea (nor do I really care) how many of us are in 2. According
to their telemetry, probably none at all. According to their prejudices,
probably just a couple of insignificant trolls.


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