CVE-2006-4677 in PHPOpenChat
Summary
by MITRE
** DISPUTED ** PHP remote file inclusion vulnerability in contrib/yabbse/poc.php in phpopenchat before 3.0.2 allows remote attackers to execute arbitrary PHP code via the sourcedir parameter. NOTE: this issue was disputed by a third-party researcher who stated that the _REQUEST parameters were dynamically unset at the beginning of the file. Another researcher noted, and CVE agrees, that the unset PHP function can be bypassed (CVE-2006-3017). If this issue is due to a vulnerability in PHP, then it should be excluded from CVE.
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Analysis
by VulDB Data Team • 08/08/2024
The vulnerability described in CVE-2006-4677 represents a remote file inclusion flaw within the phpopenchat application version 3.0.1 and earlier. This issue specifically targets the contrib/yabbse/poc.php file where the sourcedir parameter is processed without proper validation, creating an opportunity for malicious actors to inject and execute arbitrary PHP code on the target server. The vulnerability operates through a classic remote code execution vector that has been a persistent concern in web application security for many years. The flaw stems from improper input sanitization where user-supplied data directly influences file inclusion operations, allowing attackers to manipulate the application's behavior through crafted HTTP requests.
The technical implementation of this vulnerability involves the manipulation of the sourcedir parameter which is likely used to determine which directory or file should be included or sourced by the PHP application. When the application fails to properly validate or sanitize this parameter, it becomes possible for an attacker to specify arbitrary file paths or URLs that will be included and executed by the PHP interpreter. This type of vulnerability falls under the category of CWE-88, which describes improper neutralization of special elements used in an expression, specifically in the context of file inclusion operations. The vulnerability demonstrates a fundamental flaw in the application's input handling and security design, where user-controllable parameters are directly used in file inclusion contexts without adequate security controls.
The operational impact of this vulnerability is significant as it allows remote attackers to execute arbitrary code on the affected server, potentially leading to complete system compromise. An attacker could leverage this vulnerability to upload and execute malicious scripts, access sensitive data, modify system files, or establish persistent access through backdoors. The remote nature of the exploit means that attackers do not require physical access to the system or local network presence, making it particularly dangerous for publicly accessible web applications. This vulnerability would typically map to ATT&CK technique T1190, which involves exploiting vulnerabilities in remote services to gain unauthorized access, and could also be classified under T1059 for the execution of malicious code through command injection or code inclusion methods.
The disputed nature of this vulnerability stems from initial claims that the _REQUEST parameters were dynamically unset at the beginning of the file, which would theoretically prevent the vulnerability from existing. However, subsequent research confirmed that the unset function can be bypassed, as documented in CVE-2006-3017, which demonstrates that PHP's unset function is not a reliable security control against such attacks. This clarification validates the original vulnerability assessment and confirms that the application remains susceptible to remote code execution through the sourcedir parameter. The vulnerability's classification as disputed initially reflects the complexity of PHP security mechanisms and the challenges in properly analyzing legacy vulnerabilities where multiple factors can influence the actual exploitability of a given flaw.
Mitigation strategies for this vulnerability should include immediate patching of the phpopenchat application to version 3.0.2 or later where the issue has been addressed. Additionally, administrators should implement proper input validation and sanitization for all user-supplied parameters, particularly those used in file inclusion operations. The application should employ whitelisting approaches for directory and file specifications rather than allowing direct user input to determine source locations. Network-level protections such as web application firewalls and proper access controls should be implemented to limit exposure. Security practices should also include regular code reviews focusing on file inclusion operations, input validation routines, and proper parameter handling to prevent similar vulnerabilities from being introduced in future development cycles. The vulnerability underscores the importance of defense-in-depth strategies where multiple layers of security controls work together to prevent exploitation even when individual controls may be bypassed.