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backdoor in upstream xz/liblzma leading to ssh server compromise
(www.openwall.com)
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this post was submitted on 29 Mar 2024
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Is this only happened with SSH, or other network facing services using liblzma too?
We know that sshd is targeted but we don't know the full extent of the attack yet.
Also, even aside from the attack code here having unknown implications, the attacker made extensive commits to liblzma over quite a period of time, and added a lot of binary test files to the xz repo that were similar to the one that hid the exploit code here. He also was signing releases for some time prior to this, and could have released a signed tarball that differed from the git repository, as he did here. The 0.6.0 and 0.6.1 releases were contained to this backdoor aimed at sshd, but it's not impossible that he could have added vulnerabilities prior to this. Xz is used during the Debian packaging process, so code he could change is active during some kind of sensitive points on a lot of systems.
It is entirely possible that this is the first vulnerability that the attacker added, and that all the prior work was to build trust. But...it's not impossible that there were prior attacks.
The malicious code attempts to hook in to libcrypto, so potentially other services that use libcrypto could be affected too. I don't think extensive research has been done on this yet.
SSH doesn't even use liblzma. It's pulling in the malicious code via libsystemd, which does use liblzma.
Edit: "crypto" meaning cryptography of course, not cryptocurrency.