CVE-2007-3916 in SKK Tools
Summary
by MITRE
The main function in skkdic-expr.c in SKK Tools 1.2 allows local users to overwrite or delete arbitrary files via a symlink attack on a skkdic$PID temporary file.
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Analysis
by VulDB Data Team • 07/29/2019
The vulnerability identified as CVE-2007-3916 resides within the SKK Tools 1.2 software suite, specifically in the skkdic-expr.c source file where the main function executes with insufficient security controls for temporary file handling. This flaw represents a classic race condition scenario that enables local attackers to manipulate the system's file creation process through symbolic link manipulation. The vulnerability manifests when the application creates temporary files using predictable naming conventions that include process identifiers, making it susceptible to symlink-based attacks where malicious users can establish symbolic links before the legitimate file creation occurs.
The technical implementation of this vulnerability stems from improper temporary file management practices that violate fundamental security principles for file system operations. When the skkdic-expr.c function generates temporary files named skkdic$PID, it creates a window of opportunity for attackers to insert malicious symbolic links into the file system path before the legitimate file creation process completes. This race condition allows attackers to control the target of file operations, potentially enabling them to overwrite critical system files, delete important data, or inject malicious content into the application's processing pipeline. The flaw directly maps to CWE-367, which categorizes time-of-check to time-of-use vulnerabilities, and represents a significant concern for privilege escalation and data integrity compromise.
The operational impact of this vulnerability extends beyond simple file manipulation capabilities, as it can be leveraged for more sophisticated attacks within the local system environment. An attacker with local access can exploit this weakness to modify application configuration files, inject malicious code into the SKK dictionary processing pipeline, or even escalate privileges by targeting system files that the application might attempt to overwrite. The vulnerability affects any local user who can execute the skkdic-expr utility, making it particularly dangerous in multi-user environments where privilege separation is not properly enforced. This type of attack vector aligns with ATT&CK technique T1059 for executing malicious code and T1070 for clearing logs, as attackers may use such vulnerabilities to establish persistent access or cover their tracks.
Mitigation strategies for CVE-2007-3916 require immediate implementation of secure temporary file creation practices that eliminate the race condition window. System administrators should ensure that all temporary file operations use secure methods such as creating files with exclusive access permissions, utilizing secure temporary directory locations with proper access controls, and implementing atomic file creation mechanisms that prevent symbolic link manipulation. The solution involves modifying the skkdic-expr.c source code to employ proper file creation techniques that either use secure temporary file APIs or implement proper file locking mechanisms. Additionally, system-wide security hardening measures should include restricting write permissions to temporary directories, implementing proper file system access controls, and ensuring that applications do not run with elevated privileges when creating temporary files. Organizations should also consider implementing monitoring solutions that can detect suspicious file creation patterns and symbolic link manipulation attempts to provide early warning of potential exploitation attempts.