CVE-2006-3555 in PHP-Fusion
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in submit.php in PHP-Fusion before 6.01.3 allow remote attackers to inject arbitrary web script or HTML by using edit_profile.php to upload a (1) avatar or (2) forum image attachment that has a .gif or .jpg extension, and begins with a GIF header followed by JavaScript code, which is executed by Internet Explorer.
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Analysis
by VulDB Data Team • 09/17/2017
The vulnerability described in CVE-2006-3555 represents a critical cross-site scripting flaw affecting PHP-Fusion versions prior to 6.01.3. This security weakness stems from inadequate input validation and sanitization mechanisms within the platform's file upload processing system. The vulnerability specifically targets the edit_profile.php component which handles user profile modifications including avatar uploads and forum image attachments. Attackers can exploit this weakness by crafting malicious files that appear legitimate but contain embedded malicious javascript code. The attack vector leverages the fact that PHP-Fusion accepts file uploads with .gif or .jpg extensions while failing to properly validate the actual content of these files, creating a scenario where binary data containing javascript can be executed within the context of other users' browsers.
The technical implementation of this vulnerability involves exploiting the trust placed in file extensions during the upload process. When users upload profile images or forum attachments, the system validates file extensions but does not thoroughly examine the file content itself. Malicious actors can create files that begin with valid GIF headers - specifically the 6-byte signature 47 49 46 38 39 61 or 47 49 46 38 37 61 - followed by javascript code that executes when the file is displayed. Internet Explorer, which was prevalent during this time period, would interpret these files as legitimate images while simultaneously executing the embedded javascript payload. This creates a classic XSS scenario where the malicious code executes in the context of the victim's browser session, potentially allowing attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with persistent access to user sessions and potential privilege escalation opportunities. The vulnerability affects all users of the affected PHP-Fusion versions who have profile editing capabilities, making it particularly dangerous in multi-user environments where administrators and regular users share the same platform. The attack requires minimal technical expertise to execute, as it relies on standard file manipulation techniques rather than complex exploitation methods. Additionally, since the vulnerability operates at the presentation layer, it can be difficult to detect through traditional network monitoring systems, as the malicious content is embedded within legitimate-looking file uploads. This makes the vulnerability particularly insidious as it can go unnoticed while continuously compromising user sessions and potentially leading to full system compromise if attackers gain administrative privileges.
The security implications of CVE-2006-3555 align with CWE-79 which specifically addresses cross-site scripting vulnerabilities in web applications. This vulnerability also maps to ATT&CK technique T1566.001 which covers the use of malicious file uploads as a means of initial access. Organizations affected by this vulnerability should immediately implement the patch released by PHP-Fusion developers in version 6.01.3 which includes enhanced input validation and content verification for file uploads. Additional mitigations should include implementing strict file content validation using tools that verify actual file signatures rather than relying solely on extensions, implementing Content Security Policy headers to prevent execution of unauthorized scripts, and conducting regular security audits of file upload functionalities. Network segmentation and user access controls should also be reviewed to limit the potential impact of successful exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and the principle of least privilege in web application security, as it shows how a single weakness in file handling can lead to widespread session hijacking and unauthorized access to user data.