CVE-2006-3175 in mcGuestbook
Summary
by MITRE
Multiple PHP remote file inclusion vulnerabilities in mcGuestbook 1.3 allow remote attackers to execute arbitrary PHP code via a URL in the lang parameter to (1) admin.php, (2) ecrire.php, and (3) lire.php. NOTE: it was later reported that the ecrire.php vector also affects 1.2. NOTE: this issue might be limited to a race condition during installation or an improper installation, since a completed installation creates an include file that prevents external control of the $lang variable.
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Analysis
by VulDB Data Team • 08/03/2022
The vulnerability described in CVE-2006-3175 represents a critical remote code execution flaw in the mcGuestbook 1.3 web application, specifically targeting the PHP include functionality. This vulnerability falls under the category of insecure direct object references and improper input validation, which are commonly classified as CWE-20 and CWE-94 in the Common Weakness Enumeration catalog. The flaw exists in the application's handling of the lang parameter within three distinct files: admin.php, ecrire.php, and lire.php, making it particularly dangerous as it affects multiple entry points within the application's administrative interface. The vulnerability allows remote attackers to inject malicious URLs that are then processed through PHP's include mechanism, effectively enabling arbitrary code execution on the target server.
The technical implementation of this vulnerability relies on the application's improper sanitization of user-supplied input, particularly within the language parameter that is used to determine which language file to include. When an attacker provides a malicious URL in the lang parameter, the application directly incorporates this input into the include statement without proper validation or sanitization. This creates an environment where attacker-controlled content can be executed as PHP code, bypassing normal security boundaries and potentially allowing full system compromise. The vulnerability specifically affects the mcGuestbook application versions 1.2 and 1.3, with the ecrire.php file being identified as a vector that extends to the earlier version as well.
From an operational impact perspective, this vulnerability presents a severe threat to web server security as it allows attackers to execute arbitrary code with the privileges of the web server process. The implications extend beyond simple code execution to include potential data theft, system compromise, and further lateral movement within the network. Attackers could leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive data, or use the compromised server as a launch point for attacks against other systems. The vulnerability's potential for exploitation is heightened by the fact that it affects administrative functions, potentially allowing attackers to gain full control over the guestbook application and its underlying system resources. This aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1566 for credential harvesting through web applications.
The vulnerability's exploitation is particularly concerning because it operates through the standard PHP include mechanism, which is often overlooked in security reviews. The flaw essentially creates a backdoor through which attackers can inject malicious PHP code that will be executed whenever the vulnerable pages are accessed. The reported installation conditions suggest that while the vulnerability may be limited to specific scenarios, it could still be exploited during the installation process or if the application is improperly configured. This makes the vulnerability particularly dangerous as it could be exploited even in environments where proper security measures are in place, provided that the installation phase is not properly secured. Organizations should consider implementing input validation at multiple layers, including application-level filtering and web application firewalls, to prevent such vulnerabilities from being exploited in production environments. The vulnerability also underscores the importance of proper secure coding practices and input sanitization, particularly when dealing with dynamic include statements and user-supplied parameters.