CVE-2015-1319 in Settings Daemon
Summary
by MITRE
The Unity Settings Daemon before 14.04.0+14.04.20150825-0ubuntu2 and 15.04.x before 15.04.1+15.04.20150408-0ubuntu1.2 does not properly detect if the screen is locked, which allows physically proximate attackers to mount removable media while the screen is locked as demonstrated by inserting a USB thumb drive.
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability identified as CVE-2015-1319 affects the Unity Settings Daemon component in Ubuntu desktop environments, specifically impacting versions prior to the mentioned security patches. This flaw represents a significant security oversight in the desktop environment's session management capabilities, where the system fails to properly recognize when a user's session has been locked. The issue stems from inadequate state detection mechanisms within the daemon responsible for managing desktop settings and user session behaviors. When a user locks their screen through the standard locking procedure, the system should prevent certain privileged operations from being executed until proper authentication occurs. However, the Unity Settings Daemon lacks proper verification of the screen lock status, creating an exploitable gap in the security model.
The technical nature of this vulnerability can be categorized under CWE-284, which addresses improper access control mechanisms, and more specifically aligns with CWE-305, indicating authentication bypass due to improper implementation. Attackers exploiting this vulnerability can physically approach a locked workstation and perform operations that should be restricted to authenticated users. The demonstration of this weakness involves inserting removable media such as USB thumb drives while the screen remains locked, effectively bypassing the session protection mechanisms. This occurs because the daemon does not properly query or monitor the screen lock state before permitting removable media operations, allowing unauthorized physical access to trigger system actions that should require user authentication.
The operational impact of this vulnerability extends beyond simple unauthorized data access, representing a serious threat to user privacy and system integrity in environments where physical security is not guaranteed. An attacker with physical proximity to a locked workstation can potentially access sensitive data stored on removable drives, copy files, or even introduce malicious software through the USB insertion mechanism. This vulnerability particularly affects desktop environments where users frequently lock their screens for security purposes, creating a false sense of security when the system actually permits unauthorized operations. The risk is amplified in corporate or institutional settings where sensitive information may be stored on removable devices, and where unauthorized physical access could lead to data breaches or intellectual property theft. The vulnerability essentially undermines the fundamental security principle of session isolation, where locked sessions should maintain their protected state until proper authentication occurs.
Mitigation strategies for this vulnerability should include immediate application of the vendor-provided security patches that address the improper screen lock detection mechanism. System administrators should ensure that all affected Ubuntu installations are updated to versions containing the fix, specifically targeting the Unity Settings Daemon updates released in the 14.04.0+14.04.20150825-0ubuntu2 and 15.04.1+15.04.20150408-0ubuntu1 releases. Additionally, organizations should implement comprehensive security policies that require users to not only lock their screens but also to physically secure their devices when not in use. Network administrators should consider implementing additional monitoring controls to detect unauthorized removable media insertion events, particularly in high-security environments. The vulnerability also highlights the importance of proper session management in desktop environments and aligns with ATT&CK technique T1070.004, which covers indicator removal on host, as unauthorized media access could potentially be used to establish persistence or exfiltrate data through removable storage devices. Organizations should also consider implementing device encryption and access control policies that further limit the impact of such physical security breaches, ensuring that even if unauthorized access occurs through this vulnerability, the data remains protected through cryptographic measures.