CVE-2008-4477 in mon
Summary
by MITRE
alert.d/test.alert in mon 0.99.2 allows local users to overwrite arbitrary files via a symlink attack on the test.alert.log temporary file.
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Analysis
by VulDB Data Team • 08/18/2019
The vulnerability described in CVE-2008-4477 represents a classic symlink attack scenario that exploits improper handling of temporary files in the mon monitoring system version 0.99.2. This flaw resides within the alert.d/test.alert component where the system creates temporary log files without adequate security measures to prevent symbolic link manipulation by local users. The issue stems from the application's failure to validate or secure temporary file creation processes, creating an environment where malicious actors can exploit the predictable naming conventions of temporary files to redirect writes to arbitrary locations on the filesystem.
The technical implementation of this vulnerability follows a well-documented pattern where a local attacker creates a symbolic link with the same name as the temporary file test.alert.log, positioning it in the directory where the mon application will attempt to write. When the application executes its alert processing routine, it opens and writes to what it believes is a temporary file, but instead overwrites the target file pointed to by the symbolic link. This type of vulnerability maps directly to CWE-377, which addresses insecure temporary file creation practices, and CWE-378, which covers the creation of temporary files with insecure permissions. The flaw demonstrates a fundamental lack of proper file access control and temporary file management within the mon application's alert subsystem.
Operationally, this vulnerability poses significant risks to system integrity and confidentiality as local users can potentially overwrite critical system files, configuration data, or even executable components with malicious content. The impact extends beyond simple file overwrites to include potential privilege escalation scenarios where attackers might target system binaries or configuration files that are writable by the mon process. Attackers could leverage this to replace important system components, create backdoors, or corrupt system functionality. The vulnerability is particularly concerning because it requires only local user access, making it exploitable in environments where such privileges are more readily available than remote access vectors, aligning with ATT&CK technique T1068 which covers local privilege escalation through exploitation of system vulnerabilities.
Mitigation strategies for this vulnerability should focus on implementing secure temporary file creation practices that prevent symbolic link attacks. The mon application should be modified to use secure temporary file creation functions that ensure atomic file creation with appropriate permissions and verify that the target file path does not contain symbolic links. System administrators should also implement proper file permissions and access controls on the alert.d directory and its contents. The recommended approach involves using functions like mkstemp() or similar secure temporary file creation APIs that guarantee file creation without symbolic link vulnerabilities. Additionally, the system should validate all temporary file paths and ensure that the application operates with minimal required privileges to reduce the potential impact of successful exploitation. Regular security audits should verify that no other components of the mon system suffer from similar temporary file handling issues, and system monitoring should be implemented to detect unauthorized file modifications in critical directories.