How to defuse XZ Backdoor (or alike) in SSH Daemon

Background

Someone planted a backdoor in XZ compression, which is believed to affect SSH. More details can be found. Although it was never shipped to production version of any distro. Even if you are using unaffected version I suggest you defuse any similar backdoors.

Then you can restart your sshd

systemctl cat sshd
systemctl restart sshd

NOTE: replace "sshd.service" with "ssh.service" for Debian/Ubuntu systems.

Why?

We got lucky and caught this one. We don't know all similar backdoors. The suspect have been contributing to many projects for more than 2.5+ years.

Quote

While not scaremongering, it is important to be clear that at this stage, we got lucky, and there may well be other effects of the infected liblzma.

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There are concerns some other projects are affected (either by themselves or changes to other projects were made to facilitate the xz backdoor). I want to avoid a witch-hunt but listing some examples here which are already been linked widely to give some commentary.

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