- Jan 24, 2011
- 9,378
A sysadmin has developed 48 characters of code that he claims can crash most popular Linux distributions.
Andrew Ayer, a Linux administrator and founder of SSLMate, explains his code works by crashing systemd, an open-source init system that is used to boot up most Linux distributions.
Users can choose to run systemd as the first processes a Linux distribution executes upon boot-up, otherwise known as Process ID 1.
Under those circumstances, Ayer warns a local user can abuse his code,
, to cause a denial-of-service condition on a critical system component:
"After running this command, PID 1 is hung in the pause system call. You can no longer start and stop daemons. inetd-style services no longer accept connections. You cannot cleanly reboot the system. The system feels generally unstable (e.g. ssh and su hang for 30 seconds since systemd is now integrated with the login system)."
At 48 characters long, this code is short enough to fit into a single Tweet.
According to Ayer, the problem doesn't just stop at a single vulnerability. He feels systemd is overall "defective by design" and argues the system has adopted too many features, thereby making PID 1 too complex.
Ayer concludes by urging Linux admins to not replace existing services with systemd and and application developers to not use systemd's non-standard interfaces.
Read more: https://www.grahamcluley.com/48-characters-crash-linux-distros-finds-admin/
Andrew Ayer, a Linux administrator and founder of SSLMate, explains his code works by crashing systemd, an open-source init system that is used to boot up most Linux distributions.
Users can choose to run systemd as the first processes a Linux distribution executes upon boot-up, otherwise known as Process ID 1.
Under those circumstances, Ayer warns a local user can abuse his code,
Code:
NOTIFY_SOCKET=/run/systemd/notify systemd-notify """After running this command, PID 1 is hung in the pause system call. You can no longer start and stop daemons. inetd-style services no longer accept connections. You cannot cleanly reboot the system. The system feels generally unstable (e.g. ssh and su hang for 30 seconds since systemd is now integrated with the login system)."
At 48 characters long, this code is short enough to fit into a single Tweet.
According to Ayer, the problem doesn't just stop at a single vulnerability. He feels systemd is overall "defective by design" and argues the system has adopted too many features, thereby making PID 1 too complex.
Ayer concludes by urging Linux admins to not replace existing services with systemd and and application developers to not use systemd's non-standard interfaces.
Read more: https://www.grahamcluley.com/48-characters-crash-linux-distros-finds-admin/
