CVE-2008-4979 in rancid
Summary
by MITRE
getipacctg in rancid 2.3.2~a8 allows local users to overwrite arbitrary files via a symlink attack on (1) /tmp/ipacct.#####.prefixes, (2) /tmp/ipacct.#####.sorted, (3) /tmp/ipacct.#####.pl, and (4) /tmp/ipacct.##### temporary files.
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Analysis
by VulDB Data Team • 12/04/2017
The vulnerability identified as CVE-2008-4979 affects the rancid network configuration management tool version 2.3.2~a8, specifically within the getipacctg component. This flaw represents a classic symlink attack vulnerability that enables local users to manipulate the system's temporary file handling mechanisms. The vulnerability stems from insufficient validation of temporary file creation processes, allowing malicious users to create symbolic links that point to sensitive system files or directories. The affected temporary files are created in the /tmp directory with predictable naming patterns including prefixes, sorted files, and perl script files, all following the ipacct.#####.pattern format where the hash characters represent numerical placeholders.
The technical implementation of this vulnerability relies on the principle of time-of-check to time-of-use race conditions commonly found in Unix-like systems. When the getipacctg script executes, it creates temporary files in the /tmp directory without proper atomic file creation mechanisms or adequate permission checks. Local attackers can exploit this by creating symbolic links with the same names as the expected temporary files before the legitimate process creates them, effectively redirecting file operations to arbitrary locations on the filesystem. This attack vector operates under the assumption that the target system allows local users to write to the /tmp directory, which is standard in most Unix-like environments. The vulnerability is categorized under CWE-377 as insecure temporary file creation and falls within the ATT&CK technique T1059.007 for execution through command and scripting interpreter, particularly when attackers leverage the temporary files to execute malicious code.
The operational impact of this vulnerability extends beyond simple file overwrites, as it can potentially allow privilege escalation or data manipulation attacks. An attacker who successfully executes this symlink attack could overwrite critical system files, configuration files, or even executable programs that are part of the rancid infrastructure. The consequences could range from disruption of network configuration management processes to complete system compromise, especially if the rancid processes run with elevated privileges. The vulnerability affects organizations that rely on rancid for network device configuration management, potentially exposing their infrastructure to persistent attacks where attackers establish backdoors through compromised temporary files. This risk is amplified in environments where multiple users have local access to systems running rancid, as the attack surface increases with the number of potential local adversaries.
Mitigation strategies for CVE-2008-4979 should focus on implementing proper file creation atomicity mechanisms and restricting temporary file access permissions. System administrators should ensure that the rancid installation uses secure temporary file creation methods such as mkstemp or similar atomic operations that prevent symlink attacks. The /tmp directory permissions should be carefully reviewed to limit local user write access, and the use of dedicated temporary directories with restricted permissions can help prevent such attacks. Additionally, implementing proper file ownership verification and access control lists around temporary file creation processes can significantly reduce the risk. Organizations should also consider upgrading to newer versions of rancid where these vulnerabilities have been addressed through improved file handling mechanisms and better adherence to secure coding practices that prevent race conditions in temporary file operations. Regular security audits of network management tools should include checks for similar vulnerabilities in other components that may be susceptible to symlink attacks or insecure temporary file handling.