CVE-2009-0535 in Thyme
Summary
by MITRE
Directory traversal vulnerability in export.php in Thyme 1.3 and earlier, when register_globals is disabled, allows remote attackers to read arbitrary files via a .. (dot dot) in the export_to parameter.
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Analysis
by VulDB Data Team • 11/23/2024
The vulnerability identified as CVE-2009-0535 represents a critical directory traversal flaw within the Thyme time tracking application version 1.3 and earlier. This weakness specifically affects systems where the PHP configuration parameter register_globals is disabled, which is considered a security best practice in modern web applications. The vulnerability manifests in the export.php script which processes user input through the export_to parameter without proper validation or sanitization of directory path references.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a malicious request containing directory traversal sequences such as .. (dot dot) within the export_to parameter. When the application processes this input, it fails to properly validate the path components, allowing attackers to navigate outside the intended directory structure and access arbitrary files on the server. This flaw directly maps to CWE-22, which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal vulnerabilities. The vulnerability is particularly dangerous because it can potentially allow attackers to read sensitive files such as configuration files, database credentials, or even system files that should remain inaccessible to unauthorized users.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to gain unauthorized access to critical system resources and potentially escalate privileges. When register_globals is disabled, the application should be more secure, but this vulnerability demonstrates that proper input validation remains essential regardless of other security configurations. Attackers can leverage this weakness to access not only application-specific files but potentially system files that could contain sensitive data or provide insights into the underlying system architecture. The vulnerability aligns with ATT&CK technique T1083, which covers directory and file permissions enumeration, and T1566, which covers credential access through various methods including file system access.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and sanitization within the application code. Developers should implement strict path validation that prevents directory traversal sequences from being processed, utilizing functions such as realpath() combined with proper path checking or implementing allow-list validation for acceptable file paths. The fix should ensure that all user-supplied input is properly sanitized before being used in file system operations, particularly when dealing with parameters that control file exports or other file system interactions. Additionally, implementing proper access controls and ensuring that the application runs with minimal required privileges can help limit the potential damage from such vulnerabilities. Organizations should also consider implementing web application firewalls that can detect and block directory traversal attempts, while regular security audits and code reviews should be conducted to identify similar patterns that could lead to other path traversal vulnerabilities.