backdoor in upstream xz/liblzma leading to ssh server compromise

Atemu@lemmy.ml to Linux@lemmy.ml – 518 points –
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t y for sharing.

#showerthoughts The problem is in upstream and has only entered Debian Sid/unstable. Does this mean that for example bleeding edge Arch (btw) sshd users are compromised already ?

Looks like the 5.6.1-2 release on Arch moved from using the published GitHub releases to just using the git repository directly, which as I understand avoids the exploit (because the obfuscated script to inject the exploit is only present in the packaged tarballs and not the git repo itself)

https://gitlab.archlinux.org/archlinux/packaging/packages/xz/-/commit/881385757abdc39d3cfea1c3e34ec09f637424ad

They also believe we (Arch users) are unaffected because this backdoor targeted Debian and Redhat type packaging specifically and also relied on a certain SSH configuration Arch doesn't use. To be honest while it's nice to know we're unaffected, it's not at all comforting that had the exploiter targeted Arch they would have succeeded. Just yesterday I was talking to someone about how much I love rolling release distros and now I'm feeling insecure about it.

More details here: https://gitlab.archlinux.org/archlinux/packaging/packages/xz/-/issues/2

Someone always has to be the guinea pig.

That being said, maybe there's an argument for distros that do rolling releases to have an "intentionally delayed rolling release" that just trails the regular rolling release by a fixed amount of time to provide more time for guinea pigs to run into things. If you want rolling, but can live with the delay, just use that.

OpenSuse Slowroll does pretty much that, a slightly delayed rolling release.

Arch is on 5.6.1 as of now: https://archlinux.org/packages/core/x86_64/xz/

We at Nixpkgs have barely evaded having it go to a channel used by users and we don't seem to be affected by the backdoor.

Arch had a patch rolled out yesterday [1][2][3] that switches to the git repo. On top of that the logic in the runtime shim and build script modifier was orchestrated to target Debian and RPM build systems and environments [4].

[1] https://gitlab.archlinux.org/archlinux/packaging/packages/xz/-/commit/881385757abdc39d3cfea1c3e34ec09f637424ad

[2] https://gitlab.archlinux.org/archlinux/packaging/packages/xz/-/issues/2

[3] https://security.archlinux.org/CVE-2024-3094

[4] https://www.openwall.com/lists/oss-security/2024/03/29/4

The link mentions that it is only ran as part of a debian or RPM package build. Not to mention that on Arch sshd is not linked against liblzma anyways.

It was also on Gentoo. I had this version installed for a day or two.

Since you didn't build a RPM or DEB package however, your didn't compile in the backdoor.

Yeah, it's probably fine. I also don't use systemd. I was just pointing out that another rolling release distribution had the affected version.