CVE-2011-0909 in Forums
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Vanilla Forums before 2.0.17.6 allows remote attackers to inject arbitrary web script or HTML via the p parameter to an unspecified component, a different vulnerability than CVE-2011-0526.
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Analysis
by VulDB Data Team • 02/08/2019
The vulnerability identified as CVE-2011-0909 represents a cross-site scripting flaw within Vanilla Forums software prior to version 2.0.17.6. This security weakness falls under the broader category of web application vulnerabilities that can be exploited by malicious actors to execute arbitrary code within the context of a victim's browser session. The specific vector of exploitation involves the p parameter within an unspecified component of the forum software, making it particularly concerning as it affects core functionality of the platform. The vulnerability is distinct from CVE-2011-0526, indicating that this represents a separate code path or component that was not properly sanitized for user input. This XSS vulnerability enables attackers to inject malicious scripts or HTML content that can be executed by other users who view affected pages, potentially leading to session hijacking, credential theft, or defacement of the forum content.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the Vanilla Forums application. When the p parameter is processed by the affected component, the application fails to properly escape or filter user-supplied data before rendering it in the web page context. This allows an attacker to craft malicious payloads that can be stored or executed within the victim's browser environment. The vulnerability operates at the application layer and can be exploited through various means including direct URL manipulation, form submissions, or even through social engineering techniques that prompt users to click on malicious links. According to CWE standards, this vulnerability maps to CWE-79 which specifically addresses Cross-site Scripting flaws where untrusted data is improperly handled in web applications. The attack surface is particularly broad given that forums typically contain user-generated content and are frequently accessed by diverse user bases.
The operational impact of this vulnerability extends beyond simple data corruption or display issues. Attackers can leverage this XSS flaw to steal session cookies, potentially gaining unauthorized access to user accounts and administrative privileges. The malicious scripts could redirect users to phishing sites, harvest login credentials, or even modify forum content to spread malware. Given that Vanilla Forums is a widely used platform for community discussions, the potential for widespread exploitation increases significantly. The vulnerability could be exploited to manipulate forum discussions, inject spam content, or create persistent backdoors within the platform. Organizations using affected versions of Vanilla Forums face risks of reputation damage, data breaches, and potential regulatory compliance violations. The attack chain typically involves crafting a malicious URL containing the XSS payload, distributing it through social engineering or forum posts, and waiting for victims to click the link. This makes the vulnerability particularly dangerous in community-driven environments where users trust the platform and its content.
Mitigation strategies for CVE-2011-0909 should focus on immediate patching of the Vanilla Forums software to version 2.0.17.6 or later, which contains the necessary fixes for this vulnerability. Organizations should implement comprehensive input validation and output encoding mechanisms to prevent similar issues in the future. The principle of least privilege should be applied when configuring forum components, limiting the ability of users to inject content that could be executed in other users' browsers. Web Application Firewalls can provide additional protection layers by monitoring for suspicious patterns in URL parameters and blocking known malicious payloads. Regular security assessments and code reviews should be conducted to identify potential XSS vulnerabilities in custom modifications or third-party plugins. According to ATT&CK framework, this vulnerability aligns with T1059.007 which covers Scripting and T1566 which covers Phishing, indicating that exploitation often involves both automated script delivery and social engineering tactics. Organizations should also implement Content Security Policy headers to limit script execution and prevent unauthorized code from running within the forum environment. The vulnerability underscores the critical importance of keeping web applications updated and maintaining robust input sanitization practices across all user-facing components.