CVE-2002-0499 in Linux
Summary
by MITRE
The d_path function in Linux kernel 2.2.20 and earlier, and 2.4.18 and earlier, truncates long pathnames without generating an error, which could allow local users to force programs to perform inappropriate operations on the wrong directories.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability described in CVE-2002-0499 represents a critical path traversal issue within the Linux kernel's d_path function that affects kernel versions 2.2.20 and earlier, as well as 2.4.18 and earlier. This flaw operates at the kernel level and specifically targets how the kernel handles pathname resolution and representation. The d_path function is responsible for converting a directory entry into its corresponding pathname representation, which is a fundamental operation in filesystem navigation and access control. When processing long pathnames, the function fails to properly validate or enforce length limitations, resulting in implicit truncation of pathnames without any error notification or indication to the calling processes.
The technical implementation of this vulnerability stems from inadequate bounds checking within the kernel's filesystem subsystem. When a pathname exceeds the maximum allowed length, the d_path function silently truncates the path rather than returning an error condition or throwing an exception. This truncation behavior creates a scenario where local users can manipulate the system into operating on truncated pathnames that may resolve to different directories than intended. The flaw essentially allows attackers to exploit the implicit truncation by constructing specially crafted long paths that, when truncated, point to alternative filesystem locations. This creates a path confusion attack vector where programs may inadvertently operate on directories different from those they intended to access, potentially leading to unauthorized file operations or privilege escalation.
The operational impact of this vulnerability extends beyond simple path confusion, as it fundamentally undermines the security model of filesystem access controls and privilege management within the Linux kernel. Local users who can control or influence pathname generation can exploit this vulnerability to bypass access controls, perform operations on unintended directories, or manipulate filesystem operations in ways that could lead to data compromise or system instability. The vulnerability is particularly concerning because it operates silently without generating error messages, making detection difficult for system administrators and security monitoring tools. This silent truncation can enable attackers to perform operations on system directories or files that they would not normally have access to, potentially leading to privilege escalation or data manipulation. The vulnerability affects the core kernel functionality that underpins all filesystem operations, making it a widespread security concern across all applications and services that rely on proper pathname handling.
Mitigation strategies for this vulnerability require both kernel-level patches and operational security measures to address the root cause and prevent exploitation. The primary solution involves upgrading to kernel versions that contain the appropriate fixes for the d_path function, which typically include proper bounds checking and error handling for long pathnames. System administrators should implement comprehensive kernel update policies to ensure all affected systems are patched promptly. Additional operational mitigations include monitoring for unusual filesystem access patterns, implementing strict path validation in applications that handle user-supplied input, and employing proper access control mechanisms that do not rely solely on pathname resolution. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, as attackers can exploit it to bypass access controls and operate silently within the system. The vulnerability also relates to CWE-122, which addresses buffer overflow conditions, and CWE-20, which covers input validation issues, making it a compound security weakness that requires both kernel-level and application-level remediation strategies to fully address the risk.