CVE-2007-1500 in Linux
Summary
by MITRE
The Linux Security Auditing Tool (LSAT) allows local users to overwrite arbitrary files via a symlink attack on temporary files, as demonstrated using /tmp/lsat1.lsat.
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Analysis
by VulDB Data Team • 07/17/2019
The Linux Security Auditing Tool (LSAT) vulnerability represents a critical path traversal and symbolic link attack flaw that undermines the integrity of temporary file handling mechanisms within the security auditing framework. This vulnerability specifically affects the way LSAT manages temporary files during its operational lifecycle, creating a window of opportunity for local attackers to manipulate the system's security monitoring capabilities. The flaw manifests when LSAT creates temporary files in the /tmp directory without proper validation of symbolic link existence, allowing malicious users to pre-create symbolic links that redirect file operations to arbitrary locations on the filesystem.
The technical implementation of this vulnerability stems from insufficient input validation and improper temporary file creation practices within the LSAT utility. When LSAT executes and attempts to write to temporary files, it does not verify whether these files are symbolic links or if they point to locations outside the intended scope. The specific attack vector demonstrated through /tmp/lsat1.lsat illustrates how an attacker can establish a symbolic link with the same name as the temporary file that LSAT expects to create, thereby redirecting all write operations to a location chosen by the attacker. This type of vulnerability aligns with CWE-377: Insecure Temporary File and CWE-378: Creation of Temporary File With Insecure Permissions, both of which highlight the dangers of improper temporary file handling in security-critical applications.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can be leveraged to compromise the entire security auditing process and potentially escalate privileges within the system. An attacker who successfully exploits this vulnerability can overwrite critical system files, configuration files, or even security audit logs, thereby undermining the integrity of the security monitoring infrastructure. This compromise can lead to persistent backdoors, data corruption, or the complete disabling of security auditing capabilities that organizations rely upon for compliance and threat detection. The local nature of the attack does not diminish its severity, as it can serve as a stepping stone for further compromise within a system where the attacker has already gained a foothold.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements in temporary file handling practices. The most effective immediate solution involves implementing proper file existence checks and atomic file creation mechanisms that prevent symbolic link attacks by using secure temporary file creation functions such as mkstemp() or similar atomic operations. Organizations should also implement proper file permissions and ownership verification for temporary directories, ensuring that temporary file creation occurs within restricted environments where symbolic link attacks cannot succeed. The implementation of the principle of least privilege should be enforced, limiting the ability of security tools to create files in globally accessible locations. Additionally, regular security audits should include checks for similar vulnerabilities in other system components, as this class of vulnerability affects numerous applications that handle temporary files without proper validation. This vulnerability demonstrates the importance of following secure coding practices and adheres to ATT&CK technique T1059.007: Command and Scripting Interpreter: Python, where insecure temporary file handling can be exploited through malicious scripts or direct system manipulation, highlighting the need for comprehensive security awareness training and secure development lifecycle practices across all system components.