CVE-2014-0475 in C Library
Summary
by MITRE
Multiple directory traversal vulnerabilities in GNU C Library (aka glibc or libc6) before 2.20 allow context-dependent attackers to bypass ForceCommand restrictions and possibly have other unspecified impact via a .. (dot dot) in a (1) LC_*, (2) LANG, or other locale environment variable.
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Analysis
by VulDB Data Team • 02/08/2022
The vulnerability identified as CVE-2014-0475 represents a critical directory traversal flaw within the GNU C Library that affected versions prior to 2.20. This weakness resides in how the system handles locale environment variables, specifically those beginning with LC_ or the LANG variable, creating a pathway for malicious actors to exploit the underlying operating system's security controls. The vulnerability operates through a seemingly innocuous sequence involving the use of dot-dot notation within these environment variables, which can be leveraged to manipulate the execution context of programs that rely on glibc for locale processing.
The technical implementation of this vulnerability stems from improper validation of locale environment variables within the glibc implementation of the setlocale function and related internationalization routines. When a program processes locale information from environment variables, it typically uses the provided values to determine system behavior, including path resolution for locale data files. Attackers can inject .. sequences into these variables to traverse up the directory tree, potentially bypassing security restrictions that were designed to prevent unauthorized access to system resources. This flaw specifically affects the ForceCommand restriction mechanism in SSH implementations, where attackers could circumvent access controls intended to limit user command execution.
The operational impact of CVE-2014-0475 extends beyond simple directory traversal, as it can potentially enable attackers to execute arbitrary commands or access restricted system resources. The vulnerability's context-dependent nature means that exploitation requires specific conditions, such as the presence of SSH with ForceCommand restrictions or applications that process locale information in an insecure manner. This weakness can be particularly dangerous in multi-user environments where SSH access is provided, as it may allow attackers to escalate privileges or gain unauthorized access to system resources that should be protected by access controls. The vulnerability demonstrates a classic path traversal issue that aligns with CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory.
Security implications of this vulnerability are significant, particularly when considering the widespread use of glibc across Unix-like operating systems and the critical role that locale processing plays in system functionality. The attack vector leverages the legitimate use of locale environment variables, making detection more challenging and allowing for stealthy exploitation. This vulnerability directly relates to the ATT&CK technique T1059.001, which involves executing commands through the command-line interface, and T1566, which encompasses social engineering attacks that can leverage system vulnerabilities. The flaw essentially undermines the principle of least privilege by allowing unauthorized path traversal through legitimate system interfaces, potentially enabling privilege escalation or information disclosure.
The mitigation strategy for CVE-2014-0475 requires immediate system updates to glibc versions 2.20 or later, where the vulnerability has been patched through improved validation of locale environment variables. System administrators should also implement monitoring for unusual locale variable usage patterns and consider implementing additional security controls around SSH configuration, particularly regarding ForceCommand restrictions. Organizations should conduct vulnerability assessments to identify systems running affected glibc versions and ensure that all Unix-like systems are updated to prevent exploitation. The fix typically involves strengthening input validation within the locale processing functions to prevent the interpretation of .. sequences in environment variable values, thereby preventing directory traversal attacks that could compromise system security and integrity.