CVE-2009-4887 in CMS S.Builder
Summary
by MITRE
PHP remote file inclusion vulnerability in index.php in CMS S.Builder 3.7 and earlier, when register_globals is enabled, allows remote attackers to execute arbitrary PHP code via a URL in a binn_include_path cookie. NOTE: this can also be leveraged to include and execute arbitrary local files.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability identified as CVE-2009-4887 represents a critical remote file inclusion flaw in the CMS S.Builder version 3.7 and earlier systems. This security weakness specifically targets the index.php file within the content management system and exploits a fundamental configuration issue that exists when the register_globals PHP directive is enabled. The vulnerability operates through a sophisticated attack vector that manipulates the binn_include_path cookie parameter to inject malicious URLs that the application subsequently includes and executes as PHP code. The flaw stems from the application's improper handling of user-supplied input within the cookie parameter, creating a pathway for attackers to bypass normal execution boundaries and inject arbitrary code into the system. This type of vulnerability falls under the category of CWE-88, which describes improper neutralization of special elements used in an OS command, and more specifically aligns with CWE-94, which addresses the execution of arbitrary code or commands.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass potential local file inclusion capabilities, making it particularly dangerous for attackers seeking to escalate privileges or gain deeper system access. When register_globals is enabled, PHP automatically creates global variables from request data, including cookies, which creates an environment where malicious input can be seamlessly integrated into the application's execution context. Attackers can leverage this by crafting malicious cookie values that point to remote web servers hosting exploit code or by targeting local files on the server that might contain malicious content. The vulnerability demonstrates how legacy PHP configurations can create dangerous attack surfaces when combined with insecure coding practices in web applications. This flaw operates at the intersection of configuration management issues and application logic flaws, creating a scenario where a single misconfiguration can lead to complete system compromise.
The attack chain begins with an attacker identifying the vulnerable CMS S.Builder installation and determining that register_globals is enabled on the target server. The attacker then crafts a malicious cookie value containing a URL pointing to a server under their control or a local file path that they have previously uploaded to the target system. When the vulnerable application processes this cookie through the binn_include_path parameter, it treats the supplied value as a legitimate file path and attempts to include it in the execution context. This process can be exploited to execute arbitrary PHP code remotely, potentially allowing attackers to establish persistent access, exfiltrate data, or perform other malicious activities. The vulnerability's potential for local file inclusion adds another dimension to the attack surface, as attackers might be able to leverage the same mechanism to read system files or include local malware. This vulnerability directly maps to ATT&CK technique T1190, which describes the use of remote file inclusion to execute arbitrary code, and T1059, which covers the execution of commands through various methods including code injection.
Mitigation strategies for CVE-2009-4887 require immediate action to address both the application-level flaw and the server configuration issues that enable exploitation. The primary recommendation involves disabling the register_globals directive in PHP configuration, which eliminates the fundamental condition that allows the vulnerability to be exploited. Additionally, developers should implement proper input validation and sanitization for all user-supplied data, particularly cookie values, ensuring that any input used in file inclusion operations is thoroughly validated against a whitelist of acceptable values. The application code should be updated to avoid using user-controllable variables in include or require statements, and developers should implement proper path validation to prevent directory traversal attacks. Organizations should also consider implementing web application firewalls to detect and block suspicious cookie values and monitor for anomalous file inclusion patterns. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other applications and ensure that legacy PHP configurations are properly secured. The vulnerability underscores the importance of following secure coding practices and maintaining current security configurations to prevent exploitation of known attack vectors.