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WARNING: Malicious code in current pre-release & testing versions/variants: F40 and rawhide affected - users of F40/rawhide need to respond

https://discussion.fedoraproject.org/t/warning-malicious-code-in-current-pre-release-testing-versions-variants-f40-and-rawhide-affected-users-of-f40-rawhide-need-to-respond/110683

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: Article: CVE details: https://access.redhat.com/security/cve/CVE-2024-3094 Be aware that this is CVE criticality 10: this is the highest risk factor. Also be aware that the header of the RH arti...

WARNING: Malicious code in current pre-release & testing versions/variants: F40 and rawhide affected - users of F40/rawhide need to respond

65 comments

possiblylinux127

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I'm genuinely disturbed that a person who was a core developer could just go rogue.

dan

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From what I've been reading, it sounds like they were malicious from the very beginning. The work to integrate the malware goes back to 2021. https://boehs.org/node/everything-i-know-about-the-xz-backdoor

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

Moonrise2473

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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.

dan

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That could be part of their plan though... Make people think they're from China when in reality they're a state-sponsored actor from a different country. Hard to tell at this point. The scary thing is they got very close to sneaking this malware in undetected.

A lot of critical projects are only maintained by one person who may end up burning out, so I'm surprised we haven't seen more attacks like this. Gain the trust of the maintainer (maybe fix some bugs, reply to some mailing-list posts, etc), take over maintenance, and slowly add some malware one small piece at a time, interspersed with enough legit commits that you become one of the top contributors (and thus people start implicitly trusting you).

Edit: Based on this analysis, they may have been based in a European timezone and just changed their timezone to UTC+8 before committing to Git to make it look like they were in China: https://rheaeve.substack.com/p/xz-backdoor-times-damned-times-and. Their commits were usually between 9 am and 6 pm Eastern European Time, and there are a few commits where the timezone was set to UTC+2 instead of UTC+8.

possiblylinux127

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Except China is one of the countries involved in cyber warfare

intrapt

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Pretty much every country is engaged in cyber warfare to some degree

possiblylinux127

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It is kind of sad

interdimensionalmeme

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That's what states, militaries and other competition-infected minds do. Usually they say they imagine this to protect from it, then it becomes a weapon and "oops all wars"

psmgx

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Heavily, aggressively involved in cyber activities. Previous Chinese attempts were unveiled by similar small gotchas.

Arguably that's hard to prove, and it could be NK, India, the NSA, etc., but it's not hard to believe this was part of another stream of attempts. Low ball, give it to the new guy, sorts of stuff.

US fed gov loves redhat for example, and getting into Fedora is how you get into RHEL

dan

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Based on this analysis, they may have been based in a European timezone and just changed their timezone to UTC+8 before committing to Git to make it look like they were in China: https://rheaeve.substack.com/p/xz-backdoor-times-damned-times-and. Their commits were usually between 9 am and 6 pm Eastern European Time, and there are a few commits where the timezone was set to UTC+2 instead of UTC+8.

stardreamer

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According to this post, the person involved exposed a different name at one point.

https://boehs.org/node/everything-i-know-about-the-xz-backdoor

Cheong is not a Pingyin name. It uses Romanization instead. Assuming that this isn't a false trail (unlikely, why would you expose a fake name once instead of using it all the time?) that cuts out China (Mainland) and Singapore which use the Pingyin system. Or somebody has a time machine and grabbed this guy before 1956.

Likely sources of the name would be a country/Chinese administrative zone that uses Chinese and Romanization. Which gives us Taiwan, Macau, or Hong Kong, all of which are in GMT+8. Note that two of these are technically under PRC control.

Realistically I feel this is just a rogue attacker instead of a nation state. The probability of China 1. Hiring someone from these specific regions 2. Exposing a non-pinying full name once on purpose is extremely low. Why bother with this when you have plenty of graduates from Tsinghua in Beijing? Especially after so many people desperate for jobs after COVID.

Moonrise2473

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Unrelated, I really like the idea that the author of that blog post to place the favicon near each link

Tywele

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Yeah, what if they go blue next?

(It's rogue not rouge)

delirious_owl

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I'm pretty sure you just said the same word twice

Moonrise2473

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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...

possiblylinux127

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They could of been working for Russia or someone else

Wes_Dev

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Or even a criminal organization.

possiblylinux127

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I doubt it. Criminal organizations aren't normally going around sabotaging things as that would shoot them in there own foot.

0x2d

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could this be a nation-state attack? since jiat75 spent multiple years developing a fake persona and it seems like a lot of effort was put into this

prettydarknwild

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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

56_

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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.

Auli

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Did you have SSH open to the internet?

56_

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No, this is just my personal laptop. I don't even have access to an IP address I could enable port-forwarding on.

arouene

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@Auli @56_ I have SSH open on internet… on ipv6, I’m safe. Do you think VPN open on the internet is safer ? (Think twice CVE-2024-21762…)

possiblylinux127

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I would nuke it and rebuild. If nothing else it is a good test of backups

delirious_owl

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What is the name of the software that is affected??

thatsnothowyoudoit

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Hard to tell from first glance but my guess would be this is fallout from the ongoing xz drama. Here: https://www.openwall.com/lists/oss-security/2024/03/29/4

Also: https://arstechnica.com/security/2024/03/backdoor-found-in-widely-used-linux-utility-breaks-encrypted-ssh-connections/

milicent_bystandr

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xz is the compromised package, but it in turn compromises ssh authentication

Synnr

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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.

https://news.ycombinator.com/item?id=39877312

There is also a killswitch hard-coded into it, so it doesn't affect machines of whatever state actor developed it.

https://news.ycombinator.com/item?id=39881018

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.

Thorned_Rose

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It's in the article linked:

The xz package that has already entered the current F40 pre-release versions/variants and rawhide contains malicious code.

MadBigote

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Microsoft Edge.

gnuplusmatt

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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

Deathcrow

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or substituted its own SSH host keys,

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.

gnuplusmatt

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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

possiblylinux127

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If you are on a affected system I would nuke from orbit.

gnuplusmatt

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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

possiblylinux127

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Honestly doing a fresh install is a good test of your recovery abilities. You should always have a way to restore critical content in an emergency

IsoSpandy

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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.

Auli

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Makes you wonder how many of these are out there that have not been found?

Unyieldingly

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Github has been turning into malwarehub.

Player2

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Using the F40 preview with KDE and a regular update from Discover rolled xz back to the known good version 5.4.6

Commiunism

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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.

Ludrol

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So far I was affected on termux. There is already package update.

interdimensionalmeme

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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.

Gabu

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And the one main issue with FOSS rears its ugly head – freedom of contribution also means freedom of bad contributions.

deaf_fish

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This happens in close source software too. You just don't find out about it until it gets bad enough.

kaleissin

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Bad title. This is CVE-2024-3094. Run "xz --version" to see if you are affected.

ryannathans

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"Run the affected binary to see if you have it"

1henno1

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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

Aradia

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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.

unionagainstdhmo

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Yeah that's just the title from the thread over on the Fedora forum

InnerScientist

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Can't you edit it?

unionagainstdhmo

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Yes but that would be disingenuous. The current title better captures the urgency of the situation

bitwolf

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If you are checking out the extent of damage on your system do not use ldd to check the links.

You can inadvertently executed the exploit this way.

HowManyNimons

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USE WINDOWS.

unionagainstdhmo

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No thanks. Lol. How many backdoors exist in Windows because we don't see the source? And if something is found they'll probably keep quiet about it. Happy April Fools' a whole day dedicated to people like you

HowManyNimons

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Lol triggered.

RageAgainstTheRich

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"No you are wrong." YoU aRe So tRiGgErEd! 🤓

Dumb dumb.

HowManyNimons

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The more times you ad-hom me, the weepier you look.

RageAgainstTheRich

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🤔

prettydarknwild

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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

HowManyNimons

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Hahaha irritating isn't it?

prettydarknwild

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Im not irritated, im saying that your logic is flawed, stop using some software piece due to a vulnerability is at least dumb, every software will have at least one, open source or not, we are humans, we commit errors, example: the SMB vulnerability that allowed the quick spread of WannaCry in 2017, and that was on Windows, and actually we are lucky that this happened on open source software and not in some big corporation privative software, if that was the case, we wouldnt be able to know about the backdoor until a large cyberattack happened