CVE-2007-2430 in TCExam
Summary
by MITRE
shared/code/tce_tmx.php in TCExam 4.0.011 and earlier allows remote attackers to create arbitrary PHP files in cache/ by placing file contents and directory traversal manipulations into a SessionUserLang cookie to public/code/index.php.
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Analysis
by VulDB Data Team • 09/09/2024
The vulnerability identified as CVE-2007-2430 represents a critical directory traversal and arbitrary file creation flaw within TCExam version 4.0.011 and earlier. This vulnerability exists in the shared/code/tce_tmx.php component and specifically targets the application's handling of user-provided session data through the SessionUserLang cookie parameter. The flaw allows remote attackers to manipulate the application's file system operations by injecting directory traversal sequences and file content directly into the cookie value. When the application processes this malicious cookie through the public/code/index.php endpoint, it fails to properly validate or sanitize the input before using it in file system operations within the cache/ directory.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization mechanisms within the TCExam application's session management system. The SessionUserLang cookie parameter is directly used in file system operations without proper path validation, allowing attackers to specify arbitrary file paths and content. This creates a condition where directory traversal sequences such as ../ or ../../ can be embedded within the cookie value, enabling attackers to navigate outside the intended directory structure and create files in the cache/ directory. The vulnerability manifests as a path traversal attack that bypasses normal file system access controls and permissions, effectively allowing arbitrary file creation in a location that should be restricted.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the capability to execute arbitrary code on the affected system. By creating PHP files in the cache/ directory, attackers can potentially inject malicious code that will be executed when the application processes these files. This opens the door for full system compromise, data exfiltration, and persistent access to the vulnerable server. The vulnerability affects the integrity and confidentiality of the entire TCExam application, as well as potentially exposing sensitive user data and session information. The remote nature of the attack means that exploitation can occur without requiring physical access to the system, making it particularly dangerous for web applications that handle sensitive educational data. This vulnerability aligns with CWE-22 Directory Traversal and CWE-74 Injection flaws, representing a classic combination of path traversal and code injection vulnerabilities that can lead to complete system compromise.
The recommended mitigations for this vulnerability include immediate patching of the TCExam application to version 4.0.012 or later, which contains the necessary input validation fixes. Organizations should implement strict input validation and sanitization for all cookie parameters, particularly those related to session management and user preferences. The application should enforce proper path validation to prevent directory traversal sequences from being processed in file system operations. Additionally, the cache/ directory should be configured with appropriate access controls and permissions to limit write access to only authorized processes. Network segmentation and monitoring should be implemented to detect unusual file creation patterns in the cache directory. This vulnerability demonstrates the importance of proper input validation and the principle of least privilege in web application security, as outlined in various cybersecurity frameworks including the NIST Cybersecurity Framework and MITRE ATT&CK matrix categories related to privilege escalation and code injection techniques. Organizations should also consider implementing web application firewalls and runtime application self-protection mechanisms to detect and prevent similar attacks.