CVE-2003-0202 in Metrics
Summary
by MITRE
The (1) halstead and (2) gather_stats scripts in metrics 1.0 allow local users to overwrite arbitrary files via a symlink attack on temporary files.
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Analysis
by VulDB Data Team • 04/26/2019
The vulnerability described in CVE-2003-0202 represents a classic symlink attack scenario that exploits insecure temporary file handling in system administration scripts. This issue affects the halstead and gather_stats scripts within the metrics 1.0 toolset, which are commonly used for system performance monitoring and data collection. The flaw stems from the scripts' failure to properly validate temporary file creation processes, creating opportunities for malicious local users to manipulate file operations through symbolic link manipulation.
The technical implementation of this vulnerability involves the scripts creating temporary files without sufficient security checks to ensure their uniqueness and isolation. When these scripts operate in a predictable temporary directory location, attackers can establish symbolic links with the same names as the temporary files the scripts intend to create. This allows the attacker to control what content gets written to files that should remain under the control of the legitimate system administration processes. The attack leverages the principle of time-of-check to time-of-use vulnerabilities where the script checks for file existence but does not revalidate the file's integrity before writing to it.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can enable privilege escalation attacks when the affected scripts are executed with elevated privileges. Local users who can manipulate these temporary files may gain access to sensitive system information or potentially compromise system integrity by overwriting critical configuration files or system binaries. The attack requires local access and basic system knowledge to execute successfully, making it particularly concerning in environments where multiple users share system resources. This vulnerability directly relates to CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) flaws, and demonstrates how inadequate temporary file handling can create persistent security weaknesses.
Mitigation strategies for this vulnerability involve implementing proper temporary file creation mechanisms that ensure file uniqueness and prevent symbolic link attacks. The recommended approach includes using secure temporary file creation functions that guarantee atomic file creation with appropriate permissions and verification steps. System administrators should also review script execution contexts and privileges, ensuring that administrative scripts do not run with unnecessary elevated permissions. Additionally, implementing proper file system permissions and access controls around temporary directories can prevent attackers from creating malicious symbolic links. This vulnerability exemplifies the importance of following secure coding practices as outlined in the Software Security Development Lifecycle and aligns with ATT&CK technique T1059.007 for executing scripts with elevated privileges, where the initial compromise often occurs through file manipulation rather than direct execution exploits.