Crashing systemd in one command by any user in the system
This post is in no way aimed at bashing systemd. It simply demonstrates a simple but crazy bug in systemd that could cause so much trouble for the sysadmins.
NOTIFY_SOCKET=/run/systemd/notify systemd-notify ""
Run the above command on a systemd machine, by any user and you will cause a DOS on that machine.
Without getting much into the technical aspects of the bug, I'll demonstrate what actually happens if someone run the above command.
Check this out:
I'm running the command on a Linux Mint 18 machine, which uses systemd.
And there. You can no longer restart any services, or not even reboot the system. This is what happens when you try to reboot or restart any services.
The serious thing about this bug is that any user on a system can do this and that will cause a lot of problems ( if that wasn't so obvious :D ).
For more technical information about the bug, go here https://www.agwa.name/blog/post/how_to_crash_systemd_in_one_tweet
The guy who discovered this vulnerability ( yes, I'd call this a security vulnerability ) has already opened the issue in systemd gitub page.
You can see the status of the bug here : https://github.com/systemd/systemd/issues/4234