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Backdoor in upstream xz/liblzma leading to SSH server compromise

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Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#521

Unfortunately, this is how good bad actors work: with a very long-term point of view. There is no “harmless” project any more.

Warning, drunk brain talking. But a LLM driven email based "collaborator" could play a very long gMw adding basic features to a code made whilst earning trust backed by a generated online presence. My money is on a resurgance in the Web of Trust.

Clearly a human is even better at it.

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#524

Unfortunately, this is how good bad actors work: with a very long-term point of view. There is no “harmless” project any more.

Probably a state actor. You can look far into the future when you’re working for the party.

Which like, also wouldn't be totally weird if I found out that the xz or whatever library maintainer worked for the DoE as a researcher? I kind of expect governments to be funding this stuff.

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#525

Earlier quoted context omitted.

those pipe usages are quite suspicious https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-n... https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-n... pipeing into this shell script which now uses "eval" https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-n... i guess this will be revisited and removed soon

> pipeing into this shell script which now uses "eval" I don’t actually see an issue with that `eval`. Why would one consider running `xz` followed by `eval`-ing its output more insecure than just running `xz`? If `xz` wants to do shenanigans with the privileges it already has, then it wouldn’t need `eval`’s help for that.

just take a closer look at the analysis https://www.openwall.com/lists/oss-security/2024/03/29/4

then try to understand the pattern. they backdoored by modifying the build process of packages. now consider the $XZ is also from a backdoored build and the call recognizes in the same way with parameters --robot --version and the shell environment with the hint "xz_wrap.sh" from the piped process. a lot stuff to recognize for the $XZ process that it run as part of a kernel build.

Maybe they put advanced stuff in a backdoored $XZ binary to modify the kernel in a similar way they modified lzma based packages in the build process.

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#526
post #361

I'd love to be at Microsoft right now and have the power to review this user's connection history to Github, even though VPN exists, many things can be learned from connection habits, links to ISPs, maybe even guess if VPNs were used, roundtrip time on connections can give hints. I really don't think some random guy wants to weaken ssh just to extract some petty ransomware cash from a couple targets.

> I really don't think some random guy wants to weaken ssh just to extract some petty ransomware cash from a couple targets.

Which is why there's probably nothing remotely interesting in them logs.

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#527

Unfortunately, this is how good bad actors work: with a very long-term point of view. There is no “harmless” project any more.

Warning, drunk brain talking. But a LLM driven email based "collaborator" could play a very long gMw adding basic features to a code made whilst earning trust backed by a generated online presence. My money is on a resurgance in the Web of Trust.

State level actor? China?

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#528

Unfortunately, this is how good bad actors work: with a very long-term point of view. There is no “harmless” project any more.

Warning, drunk brain talking. But a LLM driven email based "collaborator" could play a very long gMw adding basic features to a code made whilst earning trust backed by a generated online presence. My money is on a resurgance in the Web of Trust.

The web of trust is a really nice idea, but it works badly against that kind of attacks. Just consider that in the real world, most living people (all eight billions) are linked by only six degrees of separation. It really works, for code and for trusted social relations (like "I lend you 100 bucks and you pay me them back when you get your salary") mostly when you know the code author in person.

This is also not a new insight. In the beginning of the naughties, there was a web site named kuro5hin.org, which experiemented with user ratings and trust networks. It turned out impossible to prevent take-overs.

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#529

A couple of years ago I wrote a Go library that wraps the xz C code and allows you to do xz compression in Go: https://github.com/jamespfennell/xz About a week ago I received the first PR on that repo, to upgrade to 5.6.1. I thought it was odd to get such a random PR...it's not the same GitHub account as upstream though.

There was also a bug report in Debian which requested updating xz-utils to 5.6.1: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1067708

That's the same Hans Jansen mentioned here: https://boehs.org/node/everything-i-know-about-the-xz-backdo...

Re: Backdoor in upstream xz/liblzma leading to SSH server compromise

#530

I think the lesson here for packagers is that binary testdata should not be present while doing the build. It is too easy to hide things in testdata.

Nice idea, but then you just hide the attack in logo.png that gets embedded in the binary. Less useful for libraries, works plenty good for web/desktop/mobile.

This entire thread is above my pay grade, but isn’t minimizing the attack surface always a good thing?
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