CVE-2012-3452 in screensaver
Summary
by MITRE
gnome-screensaver 3.4.x before 3.4.4 and 3.5.x before 3.5.4, when multiple screens are used, only locks the screen with the active focus, which allows physically proximate attackers to bypass screen locking and access an unattended workstation.
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Analysis
by VulDB Data Team • 02/19/2019
The vulnerability identified as CVE-2012-3452 affects the gnome-screensaver component within the GNOME desktop environment, specifically impacting versions 3.4.x prior to 3.4.4 and 3.5.x prior to 3.5.4. This issue manifests when multiple display outputs are configured, creating a scenario where the screen locking mechanism fails to properly secure all connected screens. The flaw represents a significant security weakness that directly contradicts fundamental security principles of workstation protection, as it allows unauthorized physical access to systems when users are away from their desks.
The technical root cause of this vulnerability lies in the improper implementation of multi-monitor screen locking logic within the gnome-screensaver daemon. When multiple screens are detected, the system only activates the lock mechanism on the screen that currently holds the active user focus or input attention, rather than applying the lock to all connected displays. This selective locking behavior creates a security gap where an attacker can access the unlocked screen while the user is away, effectively bypassing the intended security controls. The vulnerability aligns with CWE-284 Access Control Issues, specifically manifesting as inadequate access control enforcement across multiple display outputs.
From an operational perspective, this vulnerability significantly undermines the security posture of multi-monitor workstations, particularly in corporate environments where sensitive data is frequently accessed. Attackers can exploit this weakness by physically approaching the unlocked screen while the user is away from their primary display, gaining access to potentially confidential information, applications, or system resources. The impact extends beyond simple unauthorized access to include potential data breaches, privilege escalation opportunities, and compliance violations in regulated environments where proper workstation security is mandatory.
The security implications of this vulnerability are particularly concerning given the widespread adoption of multi-monitor setups in enterprise environments and the typical usage patterns of desktop users who frequently switch between screens. This flaw represents a critical failure in the principle of least privilege and proper access control enforcement, as it allows attackers to bypass the screen lock mechanism entirely. The vulnerability also aligns with ATT&CK technique T1547.001 for Security Software Discovery and potentially T1070.004 for Indicator Removal on Host, as it creates an environment where unauthorized access can occur without detection. Organizations should implement immediate mitigations including upgrading to patched versions of gnome-screensaver, implementing additional physical security controls, and ensuring proper user education regarding workstation security practices. The vulnerability demonstrates the importance of comprehensive testing of security features across all system configurations, particularly in multi-display environments where traditional security assumptions may not hold true.