CVE-2002-0734 in Michel Valdrighi
Summary
by MITRE
b2edit.showposts.php in B2 2.0.6pre2 and earlier does not properly load the b2config.php file in some configurations, which allows remote attackers to execute arbitrary PHP code via a URL that sets the $b2inc variable to point to a malicious program stored on a remote server.
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Analysis
by VulDB Data Team • 09/14/2025
The vulnerability described in CVE-2002-0734 represents a critical remote code execution flaw in the B2 publishing platform version 2.0.6pre2 and earlier. This issue stems from improper file inclusion mechanisms within the b2edit.showposts.php script which fails to adequately validate or sanitize the $b2inc variable before using it to load configuration files. The vulnerability manifests when an attacker manipulates the URL parameters to set the $b2inc variable to reference a remote malicious file, enabling arbitrary PHP code execution on the target server. This type of vulnerability falls under the category of insecure file inclusion as classified by CWE-829, which specifically addresses the inclusion of files without proper validation of the source or content. The flaw operates at the application layer and represents a classic path traversal or file inclusion vulnerability that can be exploited to gain unauthorized access to the underlying system.
The technical implementation of this vulnerability exploits the lack of proper input validation and secure file loading practices within the B2 platform's configuration handling mechanism. When the b2edit.showposts.php script processes user-supplied input through the $b2inc variable, it does not perform adequate sanitization or verification of the file path before attempting to include or load the b2config.php file. This creates an opportunity for remote attackers to inject malicious file paths that point to external resources controlled by the attacker. The vulnerability is particularly dangerous because it allows attackers to execute arbitrary PHP code directly on the web server, potentially leading to complete system compromise. According to ATT&CK framework, this vulnerability maps to T1059.007 for PHP code execution and T1190 for exploitation of remote services, making it a significant threat vector in the context of web application attacks.
The operational impact of CVE-2002-0734 extends far beyond simple data theft or service disruption. Successful exploitation can result in complete compromise of the affected web server, allowing attackers to establish persistent backdoors, exfiltrate sensitive data, or use the compromised system as a launch point for further attacks within the network. The vulnerability's remote nature means that attackers can exploit it without requiring physical access or prior authentication, making it particularly attractive for automated exploitation campaigns. Organizations running affected versions of B2 are at risk of having their web applications turned into command and control centers for malware distribution, data exfiltration, or as part of botnet operations. The vulnerability also poses risks to the broader hosting environment, as compromised web applications can be used to attack other systems or serve as persistent threats that remain undetected for extended periods.
Mitigation strategies for CVE-2002-0734 should focus on both immediate remediation and long-term security improvements. The primary and most effective mitigation is to upgrade to a patched version of the B2 platform where the file inclusion vulnerability has been addressed through proper input validation and secure file loading mechanisms. Organizations should also implement proper web application firewalls to detect and block suspicious URL patterns that attempt to manipulate file inclusion parameters. Input validation should be strengthened to ensure that all variables used in file inclusion operations are properly sanitized and restricted to predefined safe paths. Additionally, implementing proper access controls and limiting the permissions of web server processes can reduce the potential impact of successful exploitation. Security monitoring should include detection of unusual file access patterns and attempts to load external resources through web applications. The vulnerability also highlights the importance of following secure coding practices and implementing proper input validation as outlined in OWASP Top Ten and other industry security standards to prevent similar issues in future development cycles.