CVE-2001-0109 in Linux
Summary
by MITRE
rctab in SuSE 7.0 and earlier allows local users to create or overwrite arbitrary files via a symlink attack on the rctmp temporary file.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/04/2024
The vulnerability identified as CVE-2001-0109 resides within the rctab utility distributed with SuSE Linux 7.0 and earlier versions, representing a classic temporary file creation flaw that enables local privilege escalation through symbolic link manipulation. This issue demonstrates a fundamental security weakness in how the utility handles temporary file generation, creating an environment where malicious users can exploit the system's trust in file operations. The vulnerability specifically targets the rctab utility's approach to managing temporary files during its execution lifecycle, where it creates a temporary file named rctmp without proper security measures to prevent symlink attacks.
The technical flaw manifests through the utility's insecure handling of temporary file creation, where rctab generates a temporary file without implementing proper file access controls or validation mechanisms. When the utility creates the rctmp temporary file, it does not verify whether the file already exists or whether it is a symbolic link pointing to a target location outside the intended directory. This creates a window of opportunity for local attackers to establish a symbolic link with the same name as the temporary file, effectively redirecting the utility's write operations to arbitrary locations on the filesystem. The vulnerability operates under the principle of time-of-check to time-of-use race conditions, where the utility checks for file existence and then proceeds to create or modify the file without revalidating the security context.
The operational impact of this vulnerability extends beyond simple file manipulation, as it provides local users with the capability to overwrite or create files with potentially elevated privileges. Attackers can leverage this weakness to place malicious content in critical system locations, potentially leading to privilege escalation or persistent backdoor access. The vulnerability affects the entire SuSE 7.0 and earlier release lines, indicating a widespread exposure across multiple systems that rely on this utility for configuration management. This type of vulnerability falls under the CWE-367 category of Time-of-Check to Time-of-Use race conditions, which is classified as a common weakness in software development practices that fail to properly validate security contexts during file operations.
The attack vector requires local system access but can be particularly dangerous in multi-user environments where users may have limited privileges but can exploit this vulnerability to gain unauthorized access to system resources. The attack mechanism aligns with techniques described in the MITRE ATT&CK framework under the T1059.001 technique for command and script interpreter, where local users can leverage system utilities to gain elevated privileges through file manipulation. Security practitioners should note that this vulnerability represents a fundamental flaw in Unix-like system security models where proper file access controls and atomic operations are not implemented during temporary file creation. The vulnerability's persistence across multiple versions of SuSE 7.0 demonstrates a lack of proper security review in the software development lifecycle, highlighting the importance of implementing secure coding practices and proper input validation in system utilities.
Mitigation strategies for CVE-2001-0109 involve immediate system updates to patched versions of SuSE Linux, implementing proper temporary file handling mechanisms, and establishing monitoring for unauthorized file creation activities. System administrators should ensure that all system utilities properly implement secure temporary file creation using atomic operations or proper file access controls that prevent symbolic link manipulation. The vulnerability serves as a critical reminder of the importance of proper file system security practices and the need for comprehensive security testing of system utilities. Organizations should conduct thorough security assessments of their software installations to identify similar vulnerabilities and implement proper access controls that prevent unauthorized file manipulation in temporary directories. The recommended remediation includes upgrading to patched versions of SuSE Linux, implementing proper temporary file handling in custom utilities, and establishing security monitoring to detect potential exploitation attempts through symbolic link attacks.