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Message-ID: <CAMKvgcS+nx6FytpZCygev+RD6gd0qgzxBtkhn7QgkVPpf3eKqg@mail.gmail.com>
Date: Fri, 1 May 2026 09:15:05 -0700
From: Kevin Backhouse <kevin.backhouse@...il.com>
To: oss-security@...ts.openwall.com
Cc: Solar Designer <solar@...nwall.com>
Subject: Re: 10+ CVEs in GStreamer
Localsearch improved their sandbox a few years ago to
address CVE-2023-5557. Previously, the main thread wasn't as strictly
sandboxed as the worker threads, which is how my poc for CVE-2023-43641 was
able to break out of the sandbox. But their new seccomp sandbox looks
extremely strong to me. If I remember correctly, they've made it so that
the process that parses the untrusted files cannot even send arbitrary
D-Bus messages. It's restricted to only communicating with it's parent
process, using a very limited protocol. Last time I looked, I concluded
that a sandbox escape would be hopeless. There are probably other
applications that use gstreamer which are softer targets though.
Kev
On Fri, 1 May 2026, 08:38 Demi Marie Obenour, <demiobenour@...il.com> wrote:
> On 4/30/26 19:59, Solar Designer wrote:
> > Hi,
> >>> The GStreamer library is used to parse multimedia files in Nautilus
> >>> (GNOME Files), GNOME Videos, and Rhythmbox, as well as in the
> >>> localsearch search engine (previously known as tracker-miners)
> developed
> >>> by the GNOME project. This engine is installed in many distributions as
> >>> a dependency of the tracker-extract package, which GNOME uses to
> >>> automatically parse metadata in new files. Among other things, this
> >>> service indexes all files in the user's home directory without any user
> >>> interaction. Therefore, to perform an attack, simply create a specially
> >>> crafted multimedia file in the user's home directory, and the
> >>> vulnerability will be exploited during its automatic indexing.
> >>>
> >>> In most GNOME distributions, localsearch components (tracker-miners)
> are
> >>> enabled by default and loaded as a hard dependency of the Nautilus file
> >>> manager (GNOME Files). Starting with GNOME 46, the localsearch process
> >>> runs in sandbox isolation. To disable metadata extraction, you can
> >>> delete the rules files from the /usr/share/localsearch3/extract-rules/
> >>> or /usr/share/tracker3-miners/extract-rules/ directory.
> >
> > I don't know how good or not the mentioned "sandbox isolation" is, I'd
> > welcome comments on the risks involved and potential further hardening.
> >
> > Alexander
>
> Last I checked, the sandbox was not very good. In particular, there
> were seccomp rules that were thread-scoped rather than process-scoped,
> allowing for sandbox escape. It might have improved, though.
>
> My current opinion is that it is possible to create a truly strong
> sandbox on Linux that is nearly as good as hardware virtualization.
> However, doing so requires severely limiting the number of system
> calls available. The attack surface is then mostly limited to memory
> management, which KVM also has to some degree.
> --
> Sincerely,
> Demi Marie Obenour (she/her/hers)
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