CVE-2023-5616
📋 TL;DR
This vulnerability in Ubuntu's gnome-control-center fails to accurately display SSH remote login status when systemd socket activation is used for openssh-server. This could mislead users into believing SSH access is disabled when it's actually enabled, potentially exposing the system to unauthorized remote access. Affects Ubuntu systems using gnome-control-center with systemd socket activation for SSH.
💻 Affected Systems
- gnome-control-center
📦 What is this software?
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
⚠️ Risk & Real-World Impact
Worst Case
Unauthorized remote attackers gain SSH access to a system that the user believes is protected, potentially leading to full system compromise, data theft, or lateral movement.
Likely Case
Users mistakenly leave SSH enabled when they intended to disable it, creating an unnecessary attack surface that could be discovered and exploited by attackers scanning for open SSH ports.
If Mitigated
With proper network controls and SSH hardening, even if SSH is unexpectedly enabled, strong authentication and firewall rules prevent unauthorized access.
🎯 Exploit Status
This is an information display issue rather than a traditional exploit. Attackers would need to discover the open SSH port through scanning.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: gnome-control-center 1:43.1-0ubuntu2.1 for Ubuntu 23.04, 1:41.7-0ubuntu0.22.04.13 for Ubuntu 22.04 LTS
Vendor Advisory: https://ubuntu.com/security/notices/USN-6554-1
Restart Required: No
Instructions:
1. Run 'sudo apt update' 2. Run 'sudo apt install --only-upgrade gnome-control-center' 3. No restart required, but users should restart gnome-control-center or log out/in for changes to take effect.
🔧 Temporary Workarounds
Manually verify SSH status
linuxCheck SSH service status directly instead of relying on gnome-control-center display
sudo systemctl status ssh
sudo ss -tlnp | grep :22
Disable SSH if not needed
linuxCompletely disable SSH service if remote access is not required
sudo systemctl disable --now ssh
🧯 If You Can't Patch
- Regularly verify SSH service status using systemctl commands instead of relying on GUI
- Implement network-level controls like firewall rules to restrict SSH access to trusted IPs only
🔍 How to Verify
Check if Vulnerable:
Check if using affected Ubuntu version and systemd socket activation for SSH: 'systemctl cat ssh.socket' should show socket activation enabledCheck Version:
apt-cache policy gnome-control-centerVerify Fix Applied:
Check gnome-control-center version: 'apt-cache policy gnome-control-center' should show patched version installed📡 Detection & Monitoring
Log Indicators:
- Failed SSH authentication attempts in /var/log/auth.log
- Unexpected SSH service starts in systemd logs
Network Indicators:
- Unexpected SSH port 22 open on systems where it should be closed
- SSH scanning activity from external sources
SIEM Query:
source="auth.log" AND "sshd" AND ("Failed password" OR "Invalid user")