CVE-2011-2709 in libgssglue
Summary
by MITRE
libgssapi and libgssglue before 0.4 do not properly check privileges, which allows local users to load untrusted configuration files and execute arbitrary code via the GSSAPI_MECH_CONF environment variable, as demonstrated using mount.nfs.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability identified as CVE-2011-2709 affects the gssapi and gssglue libraries version 0.4 and earlier, presenting a critical privilege escalation risk within Unix-like operating systems. This flaw resides in the manner these libraries handle configuration file loading and environment variable processing, specifically when the GSSAPI_MECH_CONF environment variable is utilized during network file system mounting operations. The vulnerability stems from insufficient validation of user-controlled inputs and improper privilege checking mechanisms that allow local attackers to manipulate the library behavior through crafted configuration file paths.
The technical implementation of this vulnerability exploits the trust placed in the GSSAPI_MECH_CONF environment variable by the affected libraries. When a local user executes a command such as mount.nfs with elevated privileges, the gssapi libraries process this environment variable without adequate validation of the file path or content. This lack of input sanitization enables attackers to specify arbitrary configuration files that can contain malicious code or commands. The flaw operates at the intersection of privilege escalation and configuration injection, where the attacker can leverage the legitimate use of environment variables to gain unauthorized code execution privileges. This represents a classic case of insecure environment variable handling that violates fundamental security principles of least privilege and input validation.
The operational impact of CVE-2011-2709 extends beyond simple code execution, as it enables local users to potentially escalate their privileges to root level access when the vulnerable libraries are invoked in privileged contexts. The attack vector becomes particularly dangerous when the affected libraries are used in system administration tools like mount.nfs, which typically run with elevated privileges to manage network file systems. This vulnerability allows attackers to bypass normal access controls and execute arbitrary code with the privileges of the process that loads the malicious configuration file. The implications are significant for networked systems where NFS mounting operations are common and where local users might have limited access but can influence system behavior through environment variable manipulation. This vulnerability directly relates to CWE-22, which addresses improper limitation of a pathname to a restricted directory, and CWE-78, which covers improper neutralization of special elements used in OS commands.
Mitigation strategies for this vulnerability require immediate patching of the affected gssapi and gssglue libraries to version 0.4 or later, where the privilege checking mechanisms have been properly implemented. System administrators should also implement strict environment variable controls, particularly for GSSAPI_MECH_CONF, by limiting its usage to trusted applications and monitoring for unauthorized modifications. Additional defensive measures include implementing proper file system permissions on configuration directories and files, using mandatory access controls such as SELinux or AppArmor, and conducting regular security audits of system binaries that utilize these libraries. The remediation process should also involve monitoring for suspicious environment variable usage patterns and implementing application whitelisting to prevent unauthorized code execution. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and environment variable manipulation, representing a common attack path that leverages the trust model between system components. Organizations should also consider implementing runtime protection mechanisms and behavioral monitoring to detect anomalous usage patterns that might indicate exploitation attempts.