CVE-2006-0050 in Linux
Summary
by MITRE
snmptrapfmt in Debian 3.0 allows local users to overwrite arbitrary files via a symlink attack on a temporary log file.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2006-0050 affects the snmptrapfmt utility distributed with Debian 3.0, representing a classic file system race condition that enables local privilege escalation through symbolic link manipulation. This flaw exists within the snmptrapfmt component of the Simple Network Management Protocol trap handling system, which is designed to process and format SNMP trap messages for logging purposes. The vulnerability arises from improper handling of temporary files during the logging process, creating a window of opportunity for malicious local users to exploit the system's file creation patterns.
The technical implementation of this vulnerability stems from the snmptrapfmt utility's failure to properly secure temporary file creation mechanisms. When the utility processes SNMP trap data, it creates temporary log files in predictable locations without adequate permission checks or atomic file creation methods. Local attackers can exploit this by creating symbolic links in the expected temporary file locations before the utility attempts to write to them. This symlink attack allows the attacker to redirect the utility's output to arbitrary files on the system, potentially overwriting critical system files or configuration data with malicious content.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it provides local users with a method to escalate privileges and potentially compromise system integrity. Attackers can leverage this weakness to overwrite system binaries, configuration files, or log files with malicious content, potentially leading to persistent backdoors or complete system compromise. The vulnerability is particularly concerning in multi-user environments where local access might be limited but still present, as it transforms limited local access into more significant system-level control. This weakness directly aligns with CWE-367, which describes the improper handling of file system race conditions, and represents a clear violation of the principle of least privilege in system design.
Mitigation strategies for CVE-2006-0050 require immediate patching of the affected Debian 3.0 systems through official security updates from the Debian project, as well as implementing proper temporary file handling mechanisms. System administrators should ensure that all temporary file operations use atomic creation methods with proper file permissions and that symbolic link checks are performed before file operations. The implementation of proper file system permissions and the use of secure temporary file creation functions such as mkstemp or mkdtemp can prevent this class of attacks. Additionally, monitoring for suspicious file creation patterns and implementing proper access controls for the snmptrapfmt utility can help detect and prevent exploitation attempts. This vulnerability demonstrates the critical importance of secure coding practices and proper temporary file management in system utilities, aligning with ATT&CK technique T1059.007 for execution through command and script interpreters, as attackers may use this vulnerability to establish persistent access through compromised logging systems. Organizations should also consider implementing automated patch management systems to ensure timely remediation of similar vulnerabilities across their infrastructure.