CVE-2001-0084 in GTK+
Summary
by MITRE
GTK+ library allows local users to specify arbitrary modules via the GTK_MODULES environmental variable, which could allow local users to gain privileges if GTK+ is used by a setuid/setgid program.
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Analysis
by VulDB Data Team • 01/11/2025
The vulnerability identified as CVE-2001-0084 resides within the GTK+ graphical toolkit library, a widely used component in Unix and Linux graphical user interfaces. This issue represents a classic privilege escalation flaw that exploits the insecure handling of environment variables in setuid/setgid applications. The GTK+ library, when invoked by programs running with elevated privileges, fails to properly sanitize the GTK_MODULES environment variable, creating a pathway for local attackers to inject malicious code modules.
The technical flaw stems from the GTK+ library's design decision to honor the GTK_MODULES environment variable without adequate validation or privilege separation. When a setuid or setgid program loads GTK+ components, it inherits the environment variables from the calling process, including GTK_MODULES. This variable typically specifies additional GTK+ modules to load, but when manipulated by a local user, it can point to malicious shared libraries that execute with the privileges of the setuid program. The vulnerability manifests because the library does not implement proper checks to prevent arbitrary module loading from untrusted sources.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it can be exploited to gain unauthorized system access through programs that rely on GTK+ for their graphical interfaces. Any application that runs with elevated privileges and uses GTK+ for its user interface becomes a potential target for exploitation. This includes system administration tools, network utilities, and various desktop applications that might be configured to run setuid. Attackers can leverage this flaw to execute arbitrary code with the privileges of the target application, potentially leading to complete system compromise.
The vulnerability aligns with CWE-276, which addresses improper privileges, and demonstrates how environment variable manipulation can bypass security controls in setuid programs. From an adversarial perspective, this flaw maps to ATT&CK technique T1068, which involves exploiting local privilege escalation vulnerabilities. The attack vector is particularly dangerous because it requires no network connectivity and can be executed from within the local system, making it difficult to detect through traditional network monitoring. The exploitation process typically involves crafting a malicious shared library that gets loaded through the GTK_MODULES variable, effectively allowing privilege escalation without requiring additional attack surfaces.
Mitigation strategies should focus on implementing proper environment variable sanitization in setuid programs, particularly those that utilize GTK+ or similar libraries. System administrators should ensure that applications running with elevated privileges do not inherit potentially dangerous environment variables from untrusted sources. The recommended approach includes explicitly clearing or validating the GTK_MODULES variable before invoking GTK+ functions, or implementing stricter privilege separation mechanisms. Additionally, the GTK+ library itself should be updated to versions that properly handle environment variables in privileged contexts, and system-wide security policies should be implemented to prevent unauthorized module loading through environment variables. Organizations should also conduct regular vulnerability assessments to identify other setuid programs that might be susceptible to similar exploitation patterns.