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Is xz 5.6.1-3+ still dangerous? (lemmy.ml)

submitted 7 months ago* (last edited 7 months ago) by [email protected] to c/[email protected]

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When the xz backdoor was discovered, I quickly uninstalled my Arch based setup with an infected version of the software and switched to a distro that shipped an older version (5.5 or 5.4 or something). I found an article which said that in 5.6.1-3 the backdoor was "fixed" by just not letting the malware part communicating with the vulnerable ssh related stuff and the actual malware is still there? (I didn't understand 80% of the technical terms and abbreviations in it ok?) Like it still sounds kinda dangerous to me, especially since many experts say that we don't know the other ways this malware can use (except for the ssh supply chain) yet. Is it true? Should I stick with the new distro for now or can I absolutely safely switch back and finally say that I use Arch btw again?

P. S. I do know that nothing is completely safe. Here I'm asking just about xz and libxzlk or whatever the name of that library is

EDIT: 69 upvotes. Nice

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[–] [email protected] 38 points 7 months ago (3 children)

To add to your point: The .deb ones are most likely safe, since it would only be on the unstable & experimental branches. Your garden variety production servers & personal computers should be fine. That is unless you're into some unusual setup like with playing around with the upcoming version, or for some reason are pulling your own xz build.

Can't speak for the .rpm tho.

[–] [email protected] 12 points 7 months ago (1 children)

Fedora 39 and 40 (which is still in beta) uses xz 5.4. Fedora 41/rawhide (essentially the development branch) was affected it seems: https://access.redhat.com/security/cve/CVE-2024-3094. CentOS Stream and RHEL have way more outdated packages than that, so they were never vulnerable to this backdoor.

openSUSE Tumbleweed (their rolling release) was affected: https://news.opensuse.org/2024/03/29/xz-backdoor/, Enterprise or Leap were unaffected.

[–] [email protected] 3 points 7 months ago

Ah, so the .rpm is pretty much like the .deb in that it's mostly unaffected. Speaking of, I think the .deb side may have VanillaOS affected since it's based on Debian's unstable branch.

[–] [email protected] 7 points 7 months ago (1 children)

Yeah, I checked myself when this was first a thing. Debian 12 and Ubuntu 22.04 latest are on 5.4 and 5.2 respectively.

[–] [email protected] 6 points 7 months ago (1 children)

Yeah, all the current LTSes should be safe. Not sure about the Ubuntu 23.10, but the next LTS (24.04) is confirmed to be affected, hence the delay.

[–] [email protected] 5 points 7 months ago (1 children)

Not quite. It wasn't confirmed to be affected, but they can't prove that the build environment itself wasn't compromised, thus the rebuild.

As a result of CVE-2024-3094 332, Canonical made the decision to remove and rebuild all binary packages that had been built for Noble Numbat after the CVE-2024-3094 332 code was committed to xz-utils (February 26th), on newly provisioned build environments. This provides us with confidence that no binary in our builds could have been affected by this emerging threat.

https://discourse.ubuntu.com/t/noble-numbat-beta-delayed-xz-liblzma-security-update/43827

And in the follow-up:

Was the vulnerable library ever in the Ubuntu 24.04 LTS (Noble Numbat) daily builds?

No.

https://discourse.ubuntu.com/t/xz-liblzma-security-update-post-2/43801

[–] [email protected] 4 points 7 months ago

Thanks for the correction!

[–] [email protected] 4 points 7 months ago

"Safe" is a strong word to use. It's safe from that specific backdoor, and it seems like the known backdoor was the main goal of the attackers, but we don't know if they're playing 4D-Chess and have already implemented another backdoor which they're actively using.