CVE-2004-1895 in Linux
Summary
by MITRE
YaST Online Update (YOU) in SuSE 8.2 and 9.0 allows local users to overwrite arbitrary files via a symlink attack on you-$USER/cookies.
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Analysis
by VulDB Data Team • 06/23/2018
The vulnerability identified as CVE-2004-1895 affects YaST Online Update (YOU) functionality within SuSE Linux 8.2 and 9.0 distributions. This represents a classic symlink attack scenario that exploits improper handling of temporary files during the update process. The flaw specifically manifests when the update mechanism creates temporary files in the you-$USER/cookies directory without adequate validation of symbolic link references, allowing local attackers to manipulate the update workflow through malicious symlink creation.
The technical implementation of this vulnerability stems from insufficient input validation and insecure temporary file handling within the YaST update framework. When the system processes online updates, it generates temporary cookie files in a predictable location that can be manipulated by local users. The vulnerability occurs because the update process does not properly check whether the target paths are legitimate files or symbolic links, enabling attackers to create symbolic links that point to sensitive system files or configuration directories. This insecure direct object reference pattern directly relates to CWE-367, which addresses time-of-check to time-of-use vulnerabilities.
The operational impact of this vulnerability extends beyond simple file overwrites, as it provides attackers with potential privilege escalation capabilities. Local users who can execute the update process can leverage this flaw to modify critical system files, potentially compromising the integrity of the entire system. The attack vector requires local access but does not necessitate elevated privileges initially, making it particularly dangerous in multi-user environments where users may have legitimate access to update mechanisms. This vulnerability aligns with ATT&CK technique T1068, which covers local privilege escalation through exploitation of system vulnerabilities.
Mitigation strategies for this vulnerability should focus on implementing proper file validation and secure temporary file handling practices. System administrators should immediately apply available patches from SuSE to address this specific flaw. The recommended approach involves modifying the update process to verify file paths and reject symbolic links before file operations commence. Additionally, implementing proper file permissions and access controls around the update directories can prevent unauthorized manipulation. Organizations should also consider implementing monitoring solutions to detect suspicious file creation patterns in temporary directories. The vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Secure Coding Practices and highlights the necessity of proper privilege separation in system update mechanisms.