CVE-2013-4326 in Red Hat
Summary
by MITRE
RealtimeKit (aka rtkit) 0.5 does not properly use D-Bus for communication with a polkit authority, which allows local users to bypass intended access restrictions by leveraging a PolkitUnixProcess PolkitSubject race condition via a (1) setuid process or (2) pkexec process, a related issue to CVE-2013-4288.
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability identified as CVE-2013-4326 affects RealtimeKit version 0.5, a component designed to provide real-time scheduling capabilities for audio and multimedia applications on Linux systems. This flaw resides in how RealtimeKit handles communication with the polkit authority through D-Bus interfaces, creating a critical security gap that undermines the intended access controls. The vulnerability specifically targets the interaction between RealtimeKit and polkit's Unix process subject handling, where the system fails to properly validate authorization contexts during the communication process. This misconfiguration allows unauthorized local users to exploit a race condition that occurs when processing PolkitUnixProcess PolkitSubject objects, effectively bypassing the security mechanisms designed to restrict access to real-time scheduling privileges.
The technical implementation of this vulnerability stems from a race condition in the D-Bus communication pathway between RealtimeKit and the polkit authority. When a setuid process or pkexec process attempts to request real-time scheduling privileges, RealtimeKit fails to properly authenticate the requesting process through polkit's authorization framework. The race condition manifests when the system processes the PolkitSubject information before the proper authorization checks are completed, allowing malicious actors to manipulate the authorization flow. This issue is particularly concerning because it leverages existing system mechanisms rather than introducing new attack vectors, making it more difficult to detect and prevent. The vulnerability specifically impacts systems where RealtimeKit is used to manage real-time audio processing, such as in multimedia applications, audio workstations, and professional audio software environments.
The operational impact of CVE-2013-4326 extends beyond simple privilege escalation, as it provides attackers with the ability to manipulate real-time scheduling policies that can significantly affect system performance and stability. Local users who exploit this vulnerability can gain elevated privileges to perform actions that should be restricted to authorized processes, potentially leading to system compromise or denial of service conditions. The attack surface is particularly wide given that setuid programs and pkexec processes are common in many Linux distributions, especially those used for desktop environments and multimedia applications. This vulnerability directly relates to CWE-362, which describes race conditions in security-critical operations, and can be mapped to ATT&CK technique T1068, which covers the exploitation of privilege escalation vulnerabilities. The impact is further amplified because real-time scheduling privileges can be used to cause system instability through priority inversion or resource exhaustion attacks, making this vulnerability particularly dangerous in multi-user or shared computing environments.
Mitigation strategies for CVE-2013-4326 require immediate system updates to patched versions of RealtimeKit and polkit components, as the vulnerability cannot be effectively addressed through configuration changes alone. Organizations should prioritize patching systems running affected versions of RealtimeKit, particularly those that utilize audio processing or multimedia applications that depend on real-time scheduling capabilities. System administrators should also implement monitoring for unauthorized access attempts to real-time scheduling privileges and review existing setuid programs to minimize the attack surface. The vulnerability demonstrates the importance of proper D-Bus security implementation and the need for comprehensive authorization checking in system components that handle privileged operations. Additional protective measures include implementing strict access controls for real-time scheduling capabilities, using application sandboxing techniques, and regularly auditing system processes that may be vulnerable to similar race condition attacks. The fix for this vulnerability typically involves correcting the timing of authorization checks within RealtimeKit's D-Bus communication layer to ensure proper validation occurs before granting real-time scheduling privileges, aligning with best practices for secure multi-threaded application development and D-Bus security management.