CVE-2023-5616 in Ubuntu gnome-control-center
Summary
by MITRE • 04/15/2025
In Ubuntu, gnome-control-center did not properly reflect SSH remote login status when the system was configured to use systemd socket activation for openssh-server. This could unknowingly leave the local machine exposed to remote SSH access contrary to expectation of the user.
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Analysis
by VulDB Data Team • 04/16/2025
The vulnerability CVE-2023-5616 affects Ubuntu systems where the gnome-control-center application fails to accurately display the SSH remote login status when the openssh-server is configured to use systemd socket activation. This issue stems from a fundamental disconnect between the graphical user interface component and the underlying system service configuration, creating a misleading representation of the system's security posture. The problem manifests when users rely on the gnome-control-center to manage SSH settings, expecting it to reflect the actual operational state of the SSH service. When systemd socket activation is enabled for openssh-server, the service only starts when an SSH connection is attempted, which means the traditional service status checks used by the control center become ineffective. This misalignment creates a dangerous scenario where users may believe SSH is disabled or configured properly, while the system remains potentially accessible to remote attackers through the SSH protocol.
The technical flaw resides in the improper integration between the gnome-control-center's user interface and the systemd socket activation mechanism for the SSH service. According to CWE-692, this represents an inadequate input validation or improper error handling that allows a security-relevant condition to persist undetected. The vulnerability exploits the difference between how systemd socket activation manages service lifecycle and how traditional service status monitoring operates within the control center's codebase. When systemd socket activation is in use, the SSH service appears as inactive in standard service status checks, but the socket listener remains ready to spawn the SSH daemon upon connection attempts. This architectural mismatch causes the gnome-control-center to display incorrect information about SSH access, potentially leading to unauthorized remote access scenarios. The flaw essentially creates a false sense of security where users can be misled about their system's actual SSH configuration state.
The operational impact of CVE-2023-5616 is significant as it undermines user expectations regarding system security controls and creates potential attack vectors for malicious actors. Users who rely on the gnome-control-center to manage SSH access may unknowingly leave their systems exposed to remote attacks when they believe SSH is disabled or properly restricted. This vulnerability particularly affects systems where administrators configure systemd socket activation for openssh-server as a performance optimization or security measure to reduce the attack surface. The misrepresentation of SSH status can lead to compliance violations in regulated environments where explicit control over remote access is required. According to ATT&CK technique T1021.004, this vulnerability could facilitate unauthorized remote access through SSH, while also potentially enabling privilege escalation if attackers can leverage the confusion around SSH status to gain system access. The impact extends beyond immediate security concerns to include potential audit and compliance issues where system administrators may not be aware of the actual SSH access configuration.
Mitigation strategies for CVE-2023-5616 should focus on both immediate remediation and long-term architectural improvements. Users should first verify their current SSH configuration through command-line tools such as systemctl status ssh and systemctl list-sockets to confirm the actual state of the SSH service and socket activation. The recommended approach involves either disabling systemd socket activation for openssh-server or ensuring that the gnome-control-center is properly updated to handle socket-activated services correctly. System administrators should implement monitoring solutions that track SSH service status independently of the GUI controls and establish regular audits of SSH access configurations. Organizations should also consider implementing additional security controls such as SSH key-based authentication, fail2ban, and network-level firewalls to provide defense-in-depth measures. The vulnerability highlights the importance of maintaining consistency between system service management and user interface representations, particularly for security-critical components. Updates to the gnome-control-center package and proper configuration management practices are essential to address this issue effectively, as the flaw represents a failure in the principle of least privilege where users may inadvertently grant unauthorized access to their systems through misleading interface information.