RegreSSHion: RCE in OpenSSH's server, on glibc-based Linux systems (qualys.com)

Article summary

A vulnerability in OpenSSH's server on glibc-based Linux systems has been discovered, allowing for remote code execution. The exploit involves a race condition that can be won with a significant number of attempts, potentially taking several hours to obtain a remote root shell. The default settings of MaxStartups can affect the exploit's feasibility. Patches are being released for various Linux distributions.

Main themes

• OpenSSH vulnerability
• Remote code execution
• Linux security
• Exploit feasibility
• Patch releases
• Security measures

What commenters say

• The exploit's success rate is influenced by the number of attempts and the system's settings, such as MaxStartups.
• Knowing a valid login name is not necessary for the exploit to work, as it targets the authentication workflow after credentials have been entered.
• Fail2ban and other security measures may not be effective against this exploit, especially if the attacker uses a large botnet.
• Some argue that fail2ban is security theater, while others see it as a useful layer of security, albeit not a fix for this specific issue.
• Patches are being released for various Linux distributions, and users are advised to update their systems as soon as possible.
• The exploit's impact may be mitigated by the time it takes to succeed, but automated attacks could still be a significant threat.
• Some users are concerned about the lack of a simple upgrade path for certain systems, such as 18.04 386, which may leave them vulnerable to this and other exploits.
• The coordination of patch releases and announcements is seen as effective in addressing this type of vulnerability.