CVE-2007-3531 in NVClock
Summary
by MITRE
The set_default_speeds function in backend/backend.c in NVidia NVClock before 0.8b2 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/nvclock temporary file.
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Analysis
by VulDB Data Team • 07/22/2019
The vulnerability described in CVE-2007-3531 represents a classic symlink attack scenario that exploits improper temporary file handling within the NVIDIA NVClock utility. This security flaw exists in the set_default_speeds function located in the backend/backend.c file of NVClock versions prior to 0.8b2. The issue manifests when the application creates temporary files in the /tmp directory without adequate security measures to prevent symbolic link manipulation by unauthorized users. The vulnerability falls under the category of insecure temporary file creation as defined by CWE-377, which specifically addresses the creation of temporary files with insufficient security protections.
The technical implementation of this flaw allows a local attacker to create a symbolic link in the /tmp directory that points to a target file of their choosing. When the vulnerable NVClock application executes the set_default_speeds function, it attempts to write to what it believes is a temporary file at /tmp/nvclock, but due to the symbolic link, it actually writes to the attacker-controlled target file. This type of attack leverages the principle of time-of-check to time-of-use vulnerability patterns where the application checks for file existence and permissions before using the file, but the file state can change between these operations. The attack vector specifically targets the /tmp directory which is commonly used for temporary file storage and typically lacks proper access controls to prevent such attacks.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it enables attackers to potentially modify critical system files, configuration data, or even executable components that could lead to privilege escalation or persistent access. The vulnerability affects any local user who can create symbolic links in the /tmp directory, making it particularly concerning in multi-user environments where proper privilege separation may not be enforced. This issue aligns with ATT&CK technique T1059.001 for executing malicious code through command-line interfaces and T1548.001 for privilege escalation through file permissions manipulation. The vulnerability demonstrates a fundamental lack of proper file access validation and secure temporary file creation practices that are essential for preventing such attacks.
Mitigation strategies for this vulnerability require immediate patching of affected NVClock versions to 0.8b2 or later, which should include proper temporary file creation mechanisms that use secure file creation patterns such as O_CREAT | O_EXCL flags or similar atomic operations that prevent symbolic link attacks. System administrators should implement proper file system permissions and access controls for the /tmp directory, ensuring that temporary files are created with restrictive permissions and that symbolic link creation is properly restricted. The fix should also include validation of file paths and the implementation of proper file access controls to prevent unauthorized modification of critical system components. Organizations should also consider implementing monitoring for suspicious file creation patterns and symbolic link manipulation in system logs to detect potential exploitation attempts. This vulnerability highlights the importance of following secure coding practices as outlined in industry standards such as the OWASP Secure Coding Practices and NIST guidelines for secure software development lifecycle implementation.