CVE-2018-8885 in screen-resolution-extra
Summary
by MITRE
screenresolution-mechanism in screen-resolution-extra 0.17.2 does not properly use the PolicyKit D-Bus API, which allows local users to bypass intended access restrictions by leveraging a race condition via a setuid or pkexec process that is mishandled in a PolicyKitService._check_permission call.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 02/24/2023
The vulnerability identified as CVE-2018-8885 resides within the screenresolution-mechanism component of the screen-resolution-extra package version 0.17.2, representing a critical flaw in the Linux desktop environment's permission handling mechanisms. This issue specifically targets the PolicyKit D-Bus API implementation, which serves as a fundamental access control framework for managing privileges in graphical desktop environments. The vulnerability stems from improper utilization of PolicyKit's D-Bus interface, creating a security gap that allows local attackers to escalate privileges without proper authorization.
The technical exploitation of this vulnerability occurs through a race condition scenario involving setuid or pkexec processes that are improperly managed within the PolicyKitService._check_permission method call. This race condition manifests when the system attempts to verify permissions for screen resolution changes while a privileged process is executing with elevated privileges. The flaw enables attackers to manipulate the timing of permission checks, allowing them to bypass intended access restrictions that should normally prevent unauthorized modifications to system display settings. This vulnerability directly violates the principle of least privilege and undermines the security model of the desktop environment.
The operational impact of CVE-2018-8885 extends beyond simple privilege escalation, as it provides attackers with the capability to modify system display configurations that may serve as a stepping stone for further exploitation. Local users who can execute malicious code on the system gain the ability to alter screen resolution settings without proper authentication, potentially enabling them to create persistent backdoors or establish covert surveillance mechanisms. The vulnerability affects desktop environments that rely on PolicyKit for access control, particularly those using the gnome-desktop package and related components. This flaw represents a significant concern for enterprise environments where desktop security is paramount, as it allows local privilege escalation without requiring additional attack vectors or complex exploitation techniques.
Mitigation strategies for this vulnerability should focus on immediate package updates to versions that contain proper PolicyKit API handling and race condition fixes. System administrators should implement comprehensive monitoring of D-Bus access patterns and permission checks to detect anomalous behavior. The vulnerability aligns with CWE-362, which describes a race condition in security-critical code sections, and maps to ATT&CK technique T1068, which covers local privilege escalation through system binary manipulation. Organizations should also consider implementing additional security controls such as mandatory access controls, privilege separation, and regular security auditing of desktop environment components to prevent similar issues from emerging in other system services. The fix requires careful attention to proper D-Bus API usage patterns and ensuring that all permission checks are atomic and properly synchronized to prevent timing-based exploitation.