CVE-2002-1472 in X11r6
Summary
by MITRE
Untrusted search path vulnerability in libX11.so in xfree86, when used in setuid or setgid programs, allows local users to gain root privileges via a modified LD_PRELOAD environment variable that points to a malicious module.
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Analysis
by VulDB Data Team • 06/13/2018
The vulnerability described in CVE-2002-1472 represents a critical security flaw in the XFree86 implementation of the X Window System library libX11.so. This issue specifically affects applications that are compiled with setuid or setgid permissions, creating a dangerous privilege escalation vector that can be exploited by local attackers to gain root privileges. The vulnerability stems from how the library handles dynamic library loading when these privileged programs are executed, creating an environment where malicious code can be injected through improper search path handling.
The technical flaw occurs within the dynamic linker's library search mechanism where libX11.so fails to properly validate or sanitize the LD_PRELOAD environment variable when processing setuid/setgid applications. When a setuid or setgid program loads libX11.so, the library processes the LD_PRELOAD variable without adequate security checks, allowing an attacker to inject malicious shared libraries that will be loaded before the legitimate system libraries. This behavior violates fundamental security principles and creates a pathway for privilege escalation that directly contradicts the principle of least privilege. The vulnerability is classified under CWE-426 as an "Untrusted Search Path" and aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" through local privilege escalation techniques.
The operational impact of this vulnerability is severe as it allows local users to execute arbitrary code with the highest system privileges. Attackers can create malicious shared libraries that mimic legitimate system functions, enabling them to bypass security controls and gain complete control over the affected system. This type of vulnerability is particularly dangerous in multi-user environments where less privileged users can exploit it to elevate their privileges to root level. The vulnerability affects systems running XFree86 implementations and can be exploited across various Unix-like operating systems that use this particular X Window System implementation. The attack requires only local access and knowledge of the target application's setuid/setgid status, making it a particularly attractive target for attackers who have already gained low-privilege access to a system.
Mitigation strategies for this vulnerability involve several layers of security controls that address both immediate remediation and long-term prevention. The most direct approach is to remove or disable setuid/setgid permissions on applications that are vulnerable to this type of attack, though this may impact legitimate functionality. System administrators should also ensure that the LD_PRELOAD environment variable is properly sanitized or restricted in setuid/setgid contexts, which can be achieved through proper application hardening and environment variable validation. Additionally, implementing proper library search path controls and using secure coding practices that avoid unsafe library loading patterns can prevent similar issues in the future. The vulnerability demonstrates the importance of adhering to security best practices in library loading mechanisms and highlights the need for comprehensive security testing of privileged applications. Regular system updates and patch management are essential to address this vulnerability, as the XFree86 implementation has been superseded by newer X.org implementations that properly handle these security considerations. Organizations should also consider implementing monitoring and detection mechanisms to identify potential exploitation attempts and maintain proper system integrity through regular security audits and privilege access reviews.