The xz package that has already entered the current F40 pre-release versions/variants and rawhide contains malicious code. This does NOT affect users of the Fedora releases (F38, F39 are thus not affected), but all users who use already F40 pre-release versions/variants or rawhide shall read this: ...
It's an extremely sophisticated attack that was hidden very well, and was only accidentally discovered by someone who noticed that rejected SSH connections (eg invalid key or password) were using more CPU power and taking 0.5s longer than they should have. https://mastodon.social/@AndresFreundTec/112180406142695845
From that post, commits set to UTC+0800 and activity between UTC 12-17 indicate that the programmer wasn't operating from California but from another country starting with C. The name is also another hint.
I'm kinda hoping it was just that a state sponsored attacker showed up on their door and said "include this snippet or else..." otherwise it's terrifying thinking of someone planning some long con like this
We are all relying on the honesty of a few overworked volunteers...
probably some agent from the country that starts with R, or from that other country that starts with C, or from one of those silly three-letter organizations
I'm on Void, and I had the malicious version installed. Updating the system downgraded xz to 5.4.6, so it seems they are on it. I'll be watching discussions to decide if my system might still be compromised.
some people in my mastodon feed are suggesting that the backdoor might have connected out to malicious infrastructure or substituted its own SSH host keys, but I can't find any clear confirmation. More info as the investigation progresses.
I guess at this point if you're on Fedora 40 or rawhide clear / regen your host keys, even after xz version rollback
why would the backdoor do that? It would immediately expose itself because every ssh client on the planet warns about changed host keys when connecting.
Perhaps it was a poorly worded way of suggesting that invalidating host keys would invalidate all client keys it could potentially generate? Either way it's a lot of speculation.
Resetting the keys and SSH config on any potentially compromised host is probably not a terrible idea
Nuke from orbit might be an overreaction, if you need that machine perhaps disable ssh or turn the machine off until later next week when the postmortems happen. If you need that trusted machine now, then yes fresh install
In turn it compromises ssh authentication allows remote code execution via system(); if the connecting SSH certificate contains the backdoor key. No user account required. Nothing logged anywhere you'd expect. Full root code execution.
It's pretty clear this is a state actor, targeting a dependency of one of the most widely used system control software on Linux systems. There are likely tens or hundreds of other actors doing the exact same thing. This one was detected purely by chance, as it wasn't even in the code for ssh.
If people ever wonder how cyber warfare could potentially cause a massive blackout and communications system interruption - this is how.
I am looking at these gaggle of posts and all of lemmy is flooded with this and then think that there is an entire Spyware OS on the other side... Which who knows what code it runs and people are chill about it. I am so thankful for this community.
Damn, I had a malicious version installed on my Arch machine. I've since done a system update which removes the backdoor, but looking more into it, it does seem that only fedora and debian(?) are affected/targeted but better safe than sorry.
Well, there's also malicious code in the proprietary binary blobs of the drivers and those run with kernel privilege.
At least that one we see what it does.
Running Ubuntu 23.10 with xz-utils 5.41 which is unaffected. Versions 5.6.0 and 5.6.1 are the malicious packages. I used Synaptic Package Manager to search for it.
AFAIK it‘s better to use rpm -q xz xz-libs (copied from the forum replies) to avoid running xz itself just in case the affected version is already installed
If you go to the post, on the comments, there is someone that is already telling you to run dnf list xz --installed. So you don't need to run xz directly.
if this happened on windows probably no one would have noticed it until a large cyberattack happened, also, using that logic no one should be using CPU's created after 1995 due to meltdown / spectre