What we know about the xz Utils backdoor that almost infected the world
What we know about the xz Utils backdoor that almost infected the world
Malicious updates made to a ubiquitous tool were a few weeks away from going mainstream.
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Specifically, SSH logins were consuming too many CPU cycles and were generating errors with valgrind, a utility for monitoring computer memory.
Through sheer luck and Freund’s careful eye, he eventually discovered the problems were the result of updates that had been made to xz Utils. On Friday, Freund took to the Open Source Security List to disclose the updates were the result of someone intentionally planting a backdoor in the compression software.
It is lucky that Andres Freund checked and found the issue in valgrind that was maybe intentionally or maybe unintentionally.
https://www.openwall.com/lists/oss-security/2024/03/29/4
I'm interested in figuring out what happened and more information on the contributor behind the attack.
Everybody keeps saying it was found by luck, but this seems like it was found by a guy who maintains his repository properly and monitors his CPU cycles diligently just to prevent this sort of thing. I guess I would call it lucky he found it so quickly, but it was definitely not found by luck.
The fact that that person happened to be looking on a system downstream to this one, while also having the context needed to pin it back to xz in particular is the lucky part. The same attack in any of countless other places wouldn't have gotten spotted the same way, or as quickly. That's not to say diligence on Freund's part wasn't a big factor here, but it's important to identify that luck was a big factor.
It's more so lucky that there was someone diligently doing that. It could've easily gone unnoticed had there not been someone like him.
Yep. It could also be found by luck a bit later, or caught in a strict process sooner or later that we won't know.
No process is perfect, but the fact this attack is super complex, with many levels of indirection on run time, detecting if it's in debug mode, forcing maintainers to disable Oss fuzzer (a tool that scans source code for bugs and vulnerabilities) and also involved social engineering and took years to get close to widespread release is to show what it takes to plant a back door on 100% Foss systems.
As opposed to closed source, where all it takes is a conversation between govt and a CEO.
to me: the most chilling thing is that someone involved in the open source ecosystem introduced this vulnerability and, if it was intentional, what else did they do?
That's what I'm most curious about. Was it government? Was it Microsoft, Apple or Google? Was it some lone hacker or group looking for money? Was it just an OSS developer that wanted revenge? It would make for a spicy story.
It looks like a state actor, but hard to tell who. The way they did it was by bullying the original overworked maintainer into making someone else a co-maintainer, and that new co-maintainer introduced the backdoor. The accounts that pressured him into adding another maintainer all appear to have been sock puppets.
It just shows how little support there is for the lone maintainers of basic utilities that we all use, and it's really something we need to do something about.
It isn't if it was intentional. It was intentional. Otherwise the exploit chain wouldn't be so convoluted.