Is xz 5.6.1-3+ still dangerous?
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
Arch wasn't affected at all, cause the backdoor trigger was only on deb and rpm distros.
However it still a good practice to update your system and leave this version behind. Anyway, Arch already updated and is no longer distributing the backdoor version, therefore 5.6.1-3 is safe
You can use Arch btw again. Actually, you never had to leave it at first
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.
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 CentOS Stream and RHEL have way more outdated packages than that, so they were never vulnerable to this backdoor.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.
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.
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.
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.
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.
https://discourse.ubuntu.com/t/noble-numbat-beta-delayed-xz-liblzma-security-update/43827
And in the follow-up:
https://discourse.ubuntu.com/t/xz-liblzma-security-update-post-2/43801
Thanks for the correction!
"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.
I see what you did there.
What I did there? o.O
I don't even know
Oh, I thought the "You can use Arch btw again." is a play on the "I use Arch, BTW."-meme. :D It's even better, because this was not intentional I guess.
Ah! Okay...
Well, it was intentionally xD
But I didn't thought it would be a funny pun hahaha
Anyway, I did it mostly because the OP also did
I see. But yours was a little bit more sneaky. And I loved it.
I know that Arch wasn't affected but it's only true for the known ssh backdoor. Afaik that thing can contain 100+ more "viruses" in it that we don't yet know about. And btw I was using a distro that was quite a bit different to Arch (no, not Manjaro) so idk if it was any safer than Debian sid
Well, until someone find a new backdoor, I call it safe again
I'll not lose my mental health to a potentially and unknown shady backdoor that could be installed or not in a lib
Well, I have a polar opposite opinion about that lol. I guess I should stick with the old version
What about all the unknown back doors in the old versions 👻
If you worry about potential other backdoors in newer XZ versions, then you should also look into your kernel, systemd, dbus etc etc. All these things, can potentially contain backdoors that no one knows about yet.
As for currently known backdoors, the Arch versions are safe.
Of course backdoors can be anywhere. I was worried about this one especially because somewhere I read that the malicious code wasn't removed but just restricted with some hacky stuff in 5.6.1-3. It turned out to be false, at least for Arch, so, in case the new information is true, I can switch back I guess. Using a "safe" version of Arch is better than running all the apps as Flatpaks that can still have the infected version of xz libraries as dependencied anyways
Well, I guess u have your answer, tho
The important thing here is to feel good with your decision
So you need to downgrade to even earlier version. Best of all, use a fork created by Joey Hess.
Does that require compiling Arch from source to avoid compatibility issues?
I don't know for sure, it depends on changes in the liblzma API. If there were any changes (backward compatible or not, usually nobody cares about forward compatibility), yes, recompiling is required.
Then it's not for me. I can't even write a Python script lol
This is the reason I keep an OpenBSD system around. Maybe it's a false sense of security, but I feel that they are pickier about the base system at least.
I have a question. Does BSD support any universal package formats?
Afaik, no. Worth mentioning is that the fundamental design of the major BSDs is to clearly separate the core OS from third party applications. But as far as just being able to use Flathub or similar, I don't think so. If any BSD has experimented in that direction my bet would be FreeBSD.
I can't use it then. I need some apps that are definitely not available natively on BSD. Thank you for the information though
No worries :) Just out of curiosity, which software?
Unfortunately telling about the software will greatly simplify my identification so I can't do it
You shouldn't use a computer at all then, your CPU contains Intel and Amd undisclosed backdoor ;)
I know about that
You don't, I'm not talking about Intel ME.
That's the only thing, us the public know about.
Well, we don’t really know if there are backdoors in the old version as well, applying your logic
I meant a little bit different thing. Someone already explained how the issue was fixed and it seems safe enough to me