CVE-2008-4951 in Dtc-common
Summary
by MITRE
dtc 0.29.6 allows local users to overwrite arbitrary files via a symlink attack on (a) /tmp/awstats.log, (b) /tmp/spam.log.#####, and (c) /tmp/spam_err.log temporary files, related to the (1) accesslog.php and (2) sa-wrapper scripts.
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Analysis
by VulDB Data Team • 10/13/2018
The vulnerability identified as CVE-2008-4951 affects the dtc software version 0.29.6 and represents a significant local privilege escalation risk through symlink attack vectors. This flaw specifically targets temporary files created during the execution of accesslog.php and sa-wrapper scripts, which are commonly used in web server log analysis and spam filtering operations. The vulnerability stems from improper handling of temporary file creation processes that do not adequately verify file ownership or existence before writing to designated locations within the /tmp directory.
The technical implementation of this vulnerability exploits the predictable naming conventions of temporary files in the /tmp directory, where attackers can create symbolic links that point to sensitive system files or directories. When the dtc software executes either accesslog.php or sa-wrapper scripts, it creates temporary files at specific locations including /tmp/awstats.log, /tmp/spam.log, and /tmp/spam_err.log without proper security checks. This design flaw allows local attackers to establish symlinks to critical system files before the legitimate software processes attempt to write to these locations, resulting in arbitrary file overwrite capabilities.
The operational impact of this vulnerability extends beyond simple file manipulation as it provides attackers with the ability to modify system-critical files such as configuration files, log files, or even executable components. Attackers could potentially overwrite system logs to hide malicious activities, modify spam filtering configurations to bypass security controls, or corrupt important data files. The vulnerability is particularly dangerous in multi-user environments where local users might not have direct access to sensitive system files but can exploit this weakness to gain elevated privileges or compromise system integrity. This issue aligns with CWE-377 vulnerability class related to insecure temporary file creation and the ATT&CK technique T1059.007 for executing malicious code through command-line interfaces.
Mitigation strategies for CVE-2008-4951 should focus on implementing proper temporary file handling mechanisms that avoid predictable naming patterns and ensure atomic file creation operations. System administrators should consider modifying the software configuration to use non-predictable temporary file locations or implement proper file permission checks before creating temporary files. The recommended approach includes using secure temporary file creation functions that guarantee file ownership and prevent race conditions. Additionally, the software should be updated to versions that address this specific vulnerability, as the original dtc 0.29.6 version contains fundamental design flaws in its temporary file management that make it susceptible to this type of attack. Organizations should also implement monitoring solutions to detect unauthorized file creation in temporary directories and establish proper access controls to limit local user privileges that could exploit such vulnerabilities.