How to fix CVE-2024-6387 – Step-by-Step Guide
CVE-2024-6387, named 'regreSSHion,' is a critical unauthenticated Remote Code Execution (RCE) vulnerability impacting OpenSSH servers. This flaw allows attackers to gain full root control on vulnerable glibc-based Linux systems. Immediate patching is essential to prevent compromise.
What is OpenSSH regreSSHion – Unauthenticated RCE?
This critical vulnerability arises from a signal handler race condition within OpenSSH's server daemon, `sshd`. It specifically affects OpenSSH versions 8.5p1 through 9.7p1 running on glibc-based Linux distributions. An attacker can exploit this flaw to execute arbitrary code with root privileges without requiring any prior authentication.
Impact and Risks for your Infrastructure
Successful exploitation of CVE-2024-6387 leads to a full root compromise of the affected SSH server. Attackers gain complete control over the system, enabling data exfiltration, service disruption, or further network penetration. This poses a severe risk to critical infrastructure and data integrity.
Step-by-Step Mitigation Guide
To mitigate CVE-2024-6387, update OpenSSH to version 9.8p1 or newer immediately. Verify the update by checking `sshd -V` or your system's package manager. Ensure the `sshd` service is restarted after the upgrade to apply the patch effectively and secure your systems.
- 1Upgrade OpenSSH to 9.8p1 or later immediately.
- 2Restrict SSH access via firewall: allow only trusted IPs on port 22.
- 3Enable fail2ban or equivalent rate-limiting to slow exploitation attempts.
- 4Set LoginGraceTime 0 in sshd_config as a temporary workaround (disables grace period).
- 5Audit SSH server logs for exploitation attempts (look for connection floods).
- 6Consider moving SSH to a non-standard port or VPN-only access (Tailscale, WireGuard).