CVE-2009-2131 in 4images
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in 4images 1.7.7 and earlier allows remote authenticated users to inject arbitrary web script or HTML by providing a crafted user_homepage parameter to member.php, and then posting a comment associated with a picture.
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Analysis
by VulDB Data Team • 12/01/2024
The vulnerability described in CVE-2009-2131 represents a classic cross-site scripting flaw that affects the 4images content management system version 1.7.7 and earlier. This issue specifically targets the member.php script which processes user input through the user_homepage parameter, creating a pathway for malicious actors to execute arbitrary web scripts or HTML code within the context of other users' browsers. The vulnerability requires authentication to exploit, meaning that attackers must first gain valid user credentials or compromise an existing account before they can leverage this weakness.
The technical mechanism of this XSS vulnerability operates through improper input validation and output encoding within the 4images application. When an authenticated user submits a comment associated with a picture, the system fails to adequately sanitize the user_homepage parameter that is passed to member.php. This parameter is then rendered in the web page without proper HTML escaping or encoding, allowing malicious script code to be executed when other users view the affected content. The vulnerability is particularly concerning because it combines multiple attack vectors - authentication bypass is not required, but the attacker must have an account to submit malicious content that will be displayed to other users.
From an operational impact perspective, this vulnerability enables attackers to perform various malicious activities including session hijacking, defacement of user profiles, redirection to malicious websites, and potential data theft from users who view compromised content. The attack chain requires an authenticated user to submit a comment, which then gets rendered on other users' screens, making this a persistent threat that can affect multiple users over time. The vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws, and aligns with ATT&CK technique T1566.001 for initial access through malicious content.
The exploitation of this vulnerability demonstrates the critical importance of proper input validation and output encoding in web applications. The 4images system fails to implement adequate sanitization of user-supplied data before rendering it in web pages, creating a persistent XSS vulnerability that can be triggered through legitimate user interactions. Security practitioners should recognize that even authenticated users can be exploited through such vulnerabilities, as the malicious code executes within the context of legitimate user sessions. This vulnerability underscores the necessity of implementing comprehensive security measures including input validation, output encoding, and proper content sanitization to prevent attackers from leveraging legitimate user accounts to compromise other users.
Mitigation strategies for this vulnerability should include immediate patching of the 4images application to version 1.7.8 or later, which contains the necessary fixes for the XSS vulnerability. Organizations should also implement proper input validation and output encoding mechanisms throughout the application, ensuring that all user-supplied data is properly sanitized before being rendered in web pages. Additional protective measures include implementing content security policies, using secure coding practices, and conducting regular security assessments to identify similar vulnerabilities in other components of the web application stack. The vulnerability also highlights the importance of user education regarding the risks of submitting untrusted content and the need for robust access controls to prevent unauthorized account compromise.