How to fix CVE-2024-6387 – Step-by-Step Guide
CVE-2024-6387, known as 'regreSSHion', is a critical unauthenticated Remote Code Execution (RCE) vulnerability affecting OpenSSH servers. It allows attackers to gain root access on vulnerable glibc-based Linux systems. Immediate patching is essential to prevent system compromise.
What is OpenSSH regreSSHion – Unauthenticated RCE?
This critical vulnerability stems from a signal handler race condition within OpenSSH's server (sshd). Specifically, it impacts OpenSSH versions 8.5p1 through 9.7p1 running on glibc-based Linux distributions. An unauthenticated attacker can exploit this flaw to execute arbitrary code with root privileges on the target system.
Impact and Risks for your Infrastructure
Exploitation of CVE-2024-6387 leads to a full root compromise of the affected SSH server. Attackers gain complete, unauthenticated control over the system, allowing for data exfiltration, service disruption, or further network penetration. This poses a severe risk to infrastructure integrity and data confidentiality.
Step-by-Step Mitigation Guide
To fix CVE-2024-6387, update your OpenSSH installation to version 9.8p1 or newer immediately. Verify the update by checking the `sshd -V` output. After patching, restart the sshd service to ensure the fix is active and review system logs for any suspicious activity.
- 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).