High

Analysis Summary

Security fixes have been made available by the FreeBSD Project maintainers to fix a high-severity vulnerability in OpenSSH that might allow attackers to remotely execute arbitrary code with elevated privileges. The vulnerability, identified as CVE-2024-7589, has a high severity CVSS score of 7.4 out of a possible 10.0.

In sshd(8), a signal handler may call a logging function that isn't safe for async signals. In case a client fails to authenticate within the predetermined 120 LoginGraceTime seconds, the signal handler is triggered. This signal handler operates behind the privileged code of sshd(8), which is not sandboxed and has full root privileges. The secure shell (SSH) protocol suite is implemented by OpenSSH, which offers encrypted and authenticated transport for a range of services, including remote shell access.

It has been stated that CVE-2024-7589 is another example of the regreSSHion issue (CVE-2024-6387), which was discovered early this month. This instance of bad code originates from the incorporation of blacklisted in FreeBSD's OpenSSH. A determined attacker may be able to take advantage of a race condition that results from executing functions that are not async-signal-safe in the privileged sshd(8) context to enable an unauthenticated remote code execution as root.

To reduce potential dangers, FreeBSD users are strongly encouraged to update to a supported version and restart sshd. If updating sshd(8) is not possible, the race condition can be fixed by restarting sshd(8) and setting LoginGraceTime to 0 in /etc/ssh/sshd_config. This modification protects the daemon from remote code execution but leaves it open to a denial-of-service attack.

Impact

• Code Execution
• Privilege Escalation

Indicators of Compromise

CVE

• CVE-2024-7589

Affected Vendors

Remediation

• Refer to FreeBSD Security Advisory for patch, upgrade, or suggested workaround information.
• Organizations must test their assets for the vulnerability mentioned above and apply the available security patch or mitigation steps as soon as possible.
• Implement multi-factor authentication to add an extra layer of security to login processes.
• Regularly monitor network activity for any unusual behavior, as this may indicate that a cyberattack is underway.
• Organizations must stay vigilant and follow best practices for cybersecurity to protect their systems and data from potential threats. This includes regularly updating software and implementing strong access controls and monitoring tools.
• Develop a comprehensive incident response plan to respond effectively in case of a security breach or data leakage.
• Maintain regular backups of critical data and systems to ensure data recovery in case of a security incident.
• Adhere to security best practices, including the principle of least privilege, and ensure that users and applications have only the necessary permissions.
• Establish a robust patch management process to ensure that security patches are evaluated, tested, and applied promptly.
• Conduct security audits and assessments to evaluate the overall security posture of your systems and networks.
• Implement network segmentation to contain and isolate potential threats to limit their impact on critical systems.