CVE-2008-4971 in mafft
Summary
by MITRE
mafft-homologs in mafft 6.240 allows local users to overwrite arbitrary files via a symlink attack on (1) /tmp/_vf#?????, (2) /tmp/_if#?????, (3) /tmp/_pf#?????, (4) /tmp/_af#?????, (5) /tmp/_rid#?????, (6) /tmp/_res#?????, (7) /tmp/_q#?????, and (8) /tmp/_bf#????? temporary files.
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Analysis
by VulDB Data Team • 10/14/2018
The vulnerability described in CVE-2008-4971 represents a critical file system security flaw within the mafft-homologs component of the mafft software suite version 6.240. This issue stems from improper handling of temporary files during the execution of the homologs functionality, creating a symlink attack vector that allows local users to manipulate the file system in unintended ways. The vulnerability specifically targets eight distinct temporary file paths that are created with predictable naming patterns, making them susceptible to exploitation by malicious users who can establish symbolic links to overwrite files of their choice.
The technical implementation of this vulnerability involves the creation of temporary files using predictable naming conventions that include the underscore prefix followed by specific identifiers such as vf, if, pf, af, rid, res, q, and bf. When mafft-homologs executes, it creates these temporary files in the /tmp directory without proper security checks or atomic creation mechanisms. This design flaw enables attackers to create symbolic links with the same names before the legitimate program creates the actual temporary files, thereby redirecting the program's write operations to arbitrary locations on the file system. The vulnerability is classified as a race condition attack pattern where timing is crucial for successful exploitation.
From an operational perspective, this vulnerability poses significant risks to systems running the affected mafft software, particularly in multi-user environments where local privilege escalation could occur. Attackers could leverage this weakness to overwrite critical system files, configuration files, or even files belonging to other users, potentially leading to complete system compromise. The impact extends beyond simple file overwrites as it could enable privilege escalation attacks, especially when combined with other vulnerabilities or when the mafft software is executed with elevated privileges. This vulnerability aligns with CWE-377: Insecure Temporary Files and CWE-378: Creation of Temporary Files With Insecure Permissions, both of which are classified under the broader category of insecure file handling practices.
The exploitation of this vulnerability requires local system access and knowledge of the specific temporary file naming patterns used by mafft-homologs. Attackers would typically create symbolic links in the /tmp directory with the exact naming conventions before executing the vulnerable program, then wait for the program to create the actual temporary files and overwrite the targeted files through the symbolic link mechanism. This attack pattern is consistent with the attack techniques described in the MITRE ATT&CK framework under the T1059.001 technique for command and script interpreters, as attackers might use this vulnerability to establish persistent access or escalate privileges. The vulnerability also relates to T1548.001 Privilege Escalation through the potential for local users to gain elevated access to system resources.
Mitigation strategies for this vulnerability include immediate patching of the mafft software to version 6.241 or later, which addresses the temporary file creation issues through proper atomic file creation methods and secure temporary file handling. System administrators should also implement proper file system permissions and monitoring to detect suspicious symbolic link creation activities in the /tmp directory. Additionally, the principle of least privilege should be enforced by running the mafft software with minimal required privileges and ensuring that the /tmp directory has appropriate permissions to prevent unauthorized symbolic link creation. Organizations should also consider implementing file integrity monitoring solutions to detect unauthorized file modifications that could result from successful exploitation of this vulnerability.