CVE-2013-4288 in polkit
Summary
by MITRE
Race condition in PolicyKit (aka polkit) allows local users to bypass intended PolicyKit restrictions and gain privileges by starting a setuid or pkexec process before the authorization check is performed, related to (1) the polkit_unix_process_new API function, (2) the dbus API, or (3) the --process (unix-process) option for authorization to pkcheck.
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Analysis
by VulDB Data Team • 01/08/2022
The vulnerability identified as CVE-2013-4288 represents a critical race condition within PolicyKit, a system-level authorization framework that controls access to system resources and administrative functions on Linux systems. This flaw exists in the polkit component that manages permissions for various system operations, particularly affecting processes that require elevated privileges through mechanisms like setuid binaries or the pkexec utility. The race condition creates a window of opportunity where malicious local users can exploit the timing gap between process initialization and authorization verification to bypass intended security restrictions.
The technical implementation of this vulnerability stems from the improper handling of process identification and authorization checks within the PolicyKit framework. Specifically, the flaw manifests in three distinct attack vectors that all exploit the same fundamental timing issue. The first vector involves the polkit_unix_process_new API function, where the process object creation occurs before the authorization check is completed, allowing attackers to manipulate the process context. The second vector targets the dbus API interface, where remote procedure calls can be crafted to exploit the temporal gap in authorization validation. The third vector focuses on the --process (unix-process) option for pkcheck authorization, where command-line arguments can be manipulated to exploit the race condition during process validation. These attack vectors all rely on the core principle that the authorization decision is made after the process is already running, creating a window where unauthorized actions can be performed.
The operational impact of this vulnerability is severe as it allows local users to escalate privileges without proper authorization, potentially enabling attackers to perform administrative tasks that should be restricted to authorized users only. The race condition specifically affects systems where PolicyKit is used to control access to sensitive system functions, including but not limited to package management, system configuration changes, and user account modifications. Attackers can leverage this vulnerability to execute arbitrary code with elevated privileges, potentially leading to complete system compromise. The vulnerability affects various Linux distributions that implement PolicyKit for system authorization, making it a widespread concern across the Linux ecosystem. The exploitability is particularly concerning because it requires minimal privileges to execute and can be automated, making it a preferred attack vector for privilege escalation in compromised systems.
The underlying cause of this vulnerability aligns with CWE-362, which describes a race condition flaw in software design where concurrent operations can lead to unpredictable behavior. This vulnerability also maps to ATT&CK technique T1068, which covers the use of privilege escalation techniques through race conditions and timing attacks. The flaw demonstrates poor synchronization mechanisms within the PolicyKit implementation, where process state validation occurs at inappropriate points in the execution flow. Security practitioners should note that this vulnerability highlights the importance of proper temporal ordering in authorization systems and the critical need for atomic operations when validating process contexts. The race condition occurs because the framework does not properly lock or validate process identity before performing authorization checks, allowing malicious actors to manipulate the process environment during the critical window.
Mitigation strategies for CVE-2013-4288 should include immediate patching of affected PolicyKit implementations through distribution-specific updates and security patches. System administrators should also implement additional monitoring for suspicious process execution patterns and unauthorized privilege escalation attempts. The recommended approach involves ensuring that all process identification and authorization checks occur atomically, preventing the temporal gap that enables the race condition. Organizations should also consider implementing additional security controls such as mandatory access controls and process monitoring to detect and prevent exploitation attempts. Regular security audits of authorization frameworks and timely patch management are essential to prevent similar vulnerabilities from being exploited in the future. The vulnerability underscores the necessity of proper software design principles and the importance of considering temporal aspects in security-critical code implementations.