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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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OpenSSH: race condition in sshd allows remote code execution (stackdiary.com)

submitted 4 months ago by [email protected] to c/[email protected]

26 comments fedilink hide all child comments

cross-posted from: https://lemmy.pt/post/5733711

A severe vulnerability in OpenSSH, dubbed "regreSSHion" (CVE-2024-6387), has been discovered by the Qualys Threat Research Unit, potentially exposing

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[–] [email protected] 16 points 4 months ago (4 children)

Question if I update my server and it has the new SSH (patched) package. Is that enough or do I have to restart the server as well? How can I check if the old SSH is in use currently?

[–] [email protected] 6 points 4 months ago (1 children)

Some package managers have a command to see if anything is in need of restart. Zypper has ps -s for example. I'd restart to be sure though.

[–] [email protected] 2 points 4 months ago (2 children)

My server tells me a restart would be required because of:

linux-base linux-image-6.1.0-22-amd64

Does that have anything to do with the SSH package?

[–] [email protected] 2 points 4 months ago* (last edited 4 months ago)

It sounds like it's the kernel but whether it has anything to do with ssh, I really don't know. Sometimes parts work together in surprising ways, as I learned with the recent sshd/systemd/xz exploit.

You might be fine and this was the most alarming exploit since it's very inconvenient, but personally I'd restart just to be sure.

[–] [email protected] 1 points 4 months ago

No - it's the kernel image - the actual operating system, rather than a service that runs on top of it.

If you just want to restart your ssh service after updating the packages, then "systemctl restart sshd" is all that's needed, although you should probably reboot whenever the package manager suggests as a general good habit.

[–] [email protected] 3 points 4 months ago

For anyone in RHEL / Fedora land (or using dnf somewhere else), try dnf needs-restarting to list executables that have mismatched files on disk vs memory. The -r flag will hint if a reboot is needed (due to things like kernel or glibc changes)

[–] [email protected] 1 points 4 months ago* (last edited 4 months ago)

The packages in most distros will also restart the server for you. Any existing SSH sessions will technically be running in vulnerable versions, but if I'm understanding the vulnerability correctly this isn't a problem, as they won't be trying to authenticate a user.

If you want to be sure, you can manually restart the ssh server yourself. On most distros sudo systemctl restart sshd should do it.