CVE-2001-0117 in sdiff
Summary
by MITRE
sdiff 2.7 in the diffutils package allows local users to overwrite files via a symlink attack.
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Analysis
by VulDB Data Team • 12/14/2024
The vulnerability identified as CVE-2001-0117 affects the sdiff utility version 2.7 within the diffutils package, presenting a significant security risk through symlink attack exploitation. This flaw specifically targets local users who can manipulate file permissions and symbolic links to overwrite arbitrary files on the system. The vulnerability stems from the improper handling of temporary files during the execution of sdiff, which creates a race condition that malicious users can exploit to gain unauthorized write access to critical system files.
The technical implementation of this vulnerability resides in the sdiff utility's failure to properly validate file paths when creating temporary files during diff operations. When sdiff processes two files for comparison, it generates temporary files in predictable locations without sufficient security checks. An attacker can create symbolic links in the working directory that point to sensitive system files such as /etc/passwd or /etc/shadow, and then execute sdiff in a manner that causes the utility to overwrite these target files through the symbolic link mechanism. This represents a classic race condition vulnerability where the timing of file creation and access can be manipulated by an attacker.
The operational impact of CVE-2001-0117 extends beyond simple file overwriting capabilities, as it can enable privilege escalation and system compromise when executed by users with limited access. Attackers can leverage this vulnerability to modify system configuration files, inject malicious code into critical binaries, or alter authentication mechanisms. The vulnerability is particularly dangerous in multi-user environments where local users might not have direct write permissions to sensitive system files but can exploit this weakness to gain unauthorized access. This flaw directly relates to CWE-377, which addresses insecure temporary file handling, and can be mapped to ATT&CK technique T1059.007 for privilege escalation through local exploitation.
Mitigation strategies for this vulnerability require immediate patching of the diffutils package to version 2.8 or later, which addresses the symlink attack issue through proper temporary file handling. System administrators should also implement restrictive file permissions on directories where sdiff might be executed, ensuring that users cannot create symbolic links that could interfere with the utility's operation. Additional protective measures include monitoring for unusual file modification patterns and implementing mandatory access controls such as SELinux policies that restrict temporary file creation in sensitive directories. The vulnerability demonstrates the critical importance of secure coding practices in utilities that handle file operations and highlights the need for proper input validation and temporary file management in Unix-like systems. Organizations should also consider implementing automated vulnerability scanning tools that can detect the presence of vulnerable diffutils versions and alert administrators to potential exploitation risks.