CVE-2011-0544 in phpBB
Summary
by MITRE
phpbb 3.0.x-3.0.6 has an XSS vulnerability via the [flash] BB tag.
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Analysis
by VulDB Data Team • 02/13/2024
The vulnerability identified as CVE-2011-0544 affects phpBB versions 3.0.x through 3.0.6 and represents a cross-site scripting flaw that specifically targets the [flash] BB code implementation. This vulnerability resides within the forum software's handling of user-generated content where the flash BB tag is processed without adequate input sanitization. The issue stems from the application's failure to properly escape or validate user-supplied data when rendering flash media within forum posts, creating an avenue for malicious actors to inject arbitrary javascript code that executes in the context of other users' browsers.
The technical implementation of this vulnerability exploits the inherent trust placed in BB code parsing within the phpBB framework. When a user creates a post containing a [flash] BB tag with malicious payload, the application processes this tag without proper validation of the embedded parameters. The flaw occurs at the output rendering stage where the tag's attributes are directly incorporated into HTML without appropriate sanitization measures. This allows attackers to inject javascript code that gets executed when other users view the affected posts, making it a classic persistent cross-site scripting vulnerability. The vulnerability is categorized under CWE-79 as a failure to sanitize or incorrectly sanitizing user-controllable input, and aligns with ATT&CK technique T1203 for exploitation of web applications through cross-site scripting.
The operational impact of this vulnerability extends beyond simple data theft or session hijacking, as it provides attackers with the ability to manipulate forum content and potentially redirect users to malicious sites. An attacker could craft posts containing [flash] BB tags that execute malicious javascript to steal cookies, redirect users to phishing sites, or even deliver additional malware through browser-based exploits. The vulnerability affects the integrity and confidentiality of the forum environment, potentially allowing unauthorized modifications to forum content and enabling attacks against forum users. The persistent nature of the vulnerability means that once an infected post is created, it continues to affect users who view it until the malicious content is removed from the database.
Mitigation strategies for this vulnerability require immediate implementation of security patches provided by phpBB developers, as version 3.0.7 and subsequent releases include fixes addressing the improper handling of flash BB tags. Organizations should also implement additional defensive measures such as input validation for all BB code elements, regular security scanning of forum content, and monitoring for suspicious user activity. The implementation of Content Security Policy headers can provide additional protection against script execution, while proper sanitization of user-generated content through libraries that properly escape HTML entities should be enforced. Security teams should also consider implementing web application firewalls to detect and block malicious BB code patterns, and conduct regular security assessments of forum installations to identify similar vulnerabilities in other BBCodes or forum functionality.