CVE-2011-0703 in gksu-polkit
Summary
by MITRE
In gksu-polkit before 0.0.3, the source file for xauth may contain arbitrary commands that may allow an attacker to overtake an administrator X11 session.
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Analysis
by VulDB Data Team • 02/20/2024
The vulnerability identified as CVE-2011-0703 affects gksu-polkit versions prior to 0.0.3, representing a critical security flaw in the privilege escalation mechanism for X11 sessions. This issue stems from improper handling of xauth source file contents, where arbitrary commands can be injected and executed within the context of an administrator session. The vulnerability specifically targets the gksu-polkit component which serves as a policy kit integration for gksu, facilitating graphical privilege escalation in Unix-like systems. The flaw exists in how the system processes authentication information from xauth files, creating an execution path where malicious command injection can occur during session management operations.
This vulnerability operates through a command injection vector that allows attackers to manipulate the xauth source file processing logic. When gksu-polkit handles X11 authentication data, it fails to properly sanitize or validate the contents of the xauth source file, enabling an attacker to inject malicious commands that will execute with elevated privileges. The technical implementation flaw lies in insufficient input validation and command execution sanitization within the authentication handling code path. According to CWE classification, this represents a command injection vulnerability (CWE-77) that specifically affects privilege escalation mechanisms in graphical environments. The vulnerability's impact is amplified by its ability to target administrator sessions, potentially allowing full system compromise through X11 session takeover.
The operational impact of CVE-2011-0703 is severe and far-reaching within affected environments. An attacker who can manipulate the xauth source file gains the ability to execute arbitrary commands with administrative privileges, effectively bypassing normal access controls and potentially leading to complete system compromise. This vulnerability particularly affects desktop environments where graphical privilege escalation is commonly used, such as GNOME, KDE, and other X11-based desktop managers. The attack vector requires local access to the system or the ability to modify xauth files, but once exploited, the attacker can escalate privileges to root level and maintain persistent access to the compromised session. The vulnerability aligns with ATT&CK technique T1548.003 for privilege escalation through the use of policy kit components, and T1059 for command and scripting interpreter usage in executing malicious payloads.
Mitigation strategies for this vulnerability must address both the immediate patching requirement and broader security hardening measures. The primary recommendation is to upgrade to gksu-polkit version 0.0.3 or later, which contains the necessary fixes to properly validate and sanitize xauth source file contents. System administrators should implement strict file access controls on xauth files and related authentication components, ensuring that only authorized users can modify these critical system files. Additional protective measures include implementing mandatory access controls through SELinux or AppArmor policies, monitoring for unauthorized modifications to authentication files, and conducting regular security audits of graphical privilege escalation mechanisms. The vulnerability also highlights the importance of input validation in all authentication and privilege escalation components, emphasizing the need for defense-in-depth strategies that protect against similar injection vulnerabilities across the entire system architecture.