CVE-2008-4973 in myspell
Summary
by MITRE
i2myspell in myspell 3.1 allows local users to overwrite arbitrary files via a symlink attack on (1) /tmp/i2my#####.1 and (2) /tmp/i2my#####.2 temporary files.
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Analysis
by VulDB Data Team • 10/14/2018
The vulnerability identified as CVE-2008-4973 resides within the i2myspell component of the myspell 3.1 spell-checking library, presenting a significant local privilege escalation risk through symlink attacks. This flaw affects systems where the spell-checking functionality is improperly configured to create temporary files with predictable naming patterns in the /tmp directory without adequate security measures to prevent symbolic link manipulation. The vulnerability specifically targets two temporary files named /tmp/i2my#####.1 and /tmp/i2my#####.2, where the ##### represents a numeric sequence that can be exploited by local attackers to gain unauthorized access to system resources.
The technical implementation of this vulnerability stems from insecure temporary file creation practices that violate fundamental security principles outlined in CWE-377 and CWE-378. When the i2myspell component processes spell-checking operations, it generates temporary files in the /tmp directory without proper atomic file creation mechanisms or sufficient permission controls. Attackers can exploit this by creating symbolic links with the same names as the expected temporary files before the vulnerable application attempts to write to them, effectively redirecting file operations to arbitrary locations on the filesystem. This type of attack aligns with the ATT&CK technique T1059.001 for executing malicious code through command-line interfaces and T1548.001 for privilege escalation through local exploitation.
The operational impact of this vulnerability extends beyond simple file overwrites, as it can enable attackers to modify critical system files, inject malicious code into legitimate processes, or escalate privileges to higher-privileged user accounts. Local users who can execute the spell-checking functionality gain the ability to manipulate the file system in ways that could compromise system integrity and confidentiality. The vulnerability is particularly concerning in multi-user environments where less privileged users might exploit this weakness to gain unauthorized access to system resources or to modify files that should be protected. The attack vector requires local system access but does not require network connectivity, making it a persistent threat within compromised systems.
Mitigation strategies for this vulnerability should focus on implementing proper temporary file handling mechanisms that prevent symlink attacks through techniques such as using secure temporary file creation functions, implementing proper file permission controls, and ensuring atomic file creation operations. System administrators should update to patched versions of myspell or implement workarounds such as restricting write access to the /tmp directory or using more secure temporary file locations. The vulnerability demonstrates the importance of following secure coding practices and adheres to the principles outlined in the OWASP Secure Coding Practices, specifically addressing the need for proper file handling and the avoidance of predictable temporary file names. Organizations should also implement monitoring solutions to detect suspicious file creation patterns and ensure that all system components are regularly updated to address known vulnerabilities.