CVE-2008-7123 in zKup
Summary
by MITRE
Static code injection vulnerability in admin/configuration/modifier.php in zKup CMS 2.0 through 2.3 allows remote attackers to inject arbitrary PHP code into fichiers/config.php via a null byte (%00) in the login parameter in an ajout action, which bypasses the regular expression check.
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Analysis
by VulDB Data Team • 10/19/2024
The CVE-2008-7123 vulnerability represents a critical static code injection flaw in the zKup CMS 2.0 through 2.3 versions, specifically affecting the admin/configuration/modifier.php component. This vulnerability stems from inadequate input validation and sanitization mechanisms within the application's configuration management interface. The flaw manifests when the system processes user input through the login parameter during an ajout action, creating an opportunity for remote attackers to inject malicious PHP code directly into the fichiers/config.php configuration file. The vulnerability's exploitation relies on the strategic use of null byte sequences encoded as %00, which enables attackers to circumvent existing regular expression validation checks that are designed to prevent such injections.
The technical execution of this vulnerability demonstrates a sophisticated bypass technique that exploits the fundamental weakness in the application's input handling. When the system receives the login parameter containing a null byte sequence, the regular expression validation fails to properly sanitize the input due to how the null byte terminates string processing in PHP. This creates a scenario where the malicious code gets written directly into the configuration file without proper filtering, effectively allowing attackers to inject arbitrary PHP code that will execute within the application's context. The vulnerability operates at the intersection of improper input validation and buffer handling issues, making it particularly dangerous as it can persist across application sessions and potentially grant attackers persistent access to the system.
The operational impact of CVE-2008-7123 extends far beyond simple code injection, as it can lead to complete system compromise and unauthorized access to sensitive data. Attackers can leverage this vulnerability to execute malicious commands, establish backdoors, or modify critical system configurations that control the application's behavior. The persistence of injected code in the configuration file means that the malicious payload will continue to execute every time the application processes configuration data, providing attackers with long-term access to the compromised system. This vulnerability also aligns with CWE-94, which addresses the improper validation of code in the context of dynamic code generation, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for PHP code injection, making it a significant threat to system integrity and data security.
Mitigation strategies for this vulnerability must address both the immediate exploitation vector and the underlying architectural weaknesses that enabled the flaw. Organizations should implement comprehensive input validation that properly handles null byte sequences and other potentially malicious input patterns, ensuring that all user-supplied data undergoes rigorous sanitization before being processed. The recommended approach includes applying the latest security patches from the zKup CMS vendor, implementing proper access controls to restrict administrative functions, and conducting thorough code reviews to identify similar input validation weaknesses. Additionally, deploying web application firewalls and implementing proper file permissions can help prevent unauthorized modifications to configuration files, while regular security audits should verify that no malicious code has been injected into the system. The vulnerability also underscores the importance of following secure coding practices that prevent code injection attacks through proper input validation and output encoding mechanisms.