I really don't think some random guy wants to weaken ssh just to extract some petty ransomware cash from a couple targets.
Backdoor in upstream xz/liblzma leading to SSH server compromise
361–370 of 1001 posts
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#362A 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.
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#363Yikes! Do you have any info on the individual's background or possible motivations?
I would presume it's a state actor. Generally in the blackhat world, attackers have very precise targets. They want to attack this company or this group of individuals. But someone who backdoors such a core piece of open source infrastructure wants to cast a wide net to attack as many as possible. So that fits the profile of a government intelligence agency who is interested in surveilling, well, everything. Or it co…
https://www.mail-archive.com/xz-devel@tukaani.org/msg00567.h...
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#364Yikes! Do you have any info on the individual's background or possible motivations?
I would presume it's a state actor. Generally in the blackhat world, attackers have very precise targets. They want to attack this company or this group of individuals. But someone who backdoors such a core piece of open source infrastructure wants to cast a wide net to attack as many as possible. So that fits the profile of a government intelligence agency who is interested in surveilling, well, everything. Or it co…
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#365Jai Tan's commit history on his github profile suggests he took off for Christmas, new years, and spring break. I smell an American.
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#366it wasn't the apparently newly-created identity "Hans Jansen" just asking for a new version to be uploaded, it was "Hans Jansen" providing a new version to be uploaded as a non-maintainer-upload - Debian-speak for "the maintainer is AWOL, someone else is uploading their package". if "Hans Jansen" is another attacker then they did this cleverly, providing the new - compromised - upstream tarballs in an innocent-looking way and avoiding anyone examining the upstream diff.
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#367Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#368Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#369> openssh does not directly use liblzma. However debian and several other distributions patch openssh to support systemd notification, and libsystemd does depend on lzma. The systemd notification protocol could have been as simple as just writing a newline to a pipe, but instead you have to link to the libsystemd C library, so now security-critical daemons like openssh have additional dependencies like liblzma loaded…
> The systemd notification protocol could have been as simple as just writing a newline to a pipe It basically is. libsystemd links to liblzma for other features not related to notifications. (The protocol is that systemd passes the path to a unix socket in the `NOTIFY_SOCKET` env variable, and the daemon writes "READY=1" into it.)
Re: Backdoor in upstream xz/liblzma leading to SSH server compromise
#370For those panicking, here are some key things to look for, based on the writeup: - A very recent version of liblzma5 - 5.6.0 or 5.6.1. This was added in the last month or so. If you're not on a rolling release distro, your version is probably older. - A debian or RPM based distro of Linux on x86_64. In an apparent attempt to make reverse engineering harder, it does not seem to apply when built outside of deb or rpm p…
Ubuntu still ships 5.4.5 on 24.03 (atm). I did a quick diff of the source (.orig file from packages.ubuntu.com) and the content mostly matched the 5.4.5 github tag except for Changelog and some translation files. It does match the tarball content, though. So for 5.4.5 the tagged release and download on github differ. It does change format strings, e.g. +#: src/xz/args.c:735 +#, fuzzy +#| msgid "%s: With --format=raw,…