CVE-2005-4603 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in printthread.php in MyBB 1.0.1 and earlier allows remote attackers to inject arbitrary web script or HTML via a thread message, which is not properly sanitized in the print view of the thread.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2005-4603 represents a classic cross-site scripting flaw that existed in MyBB version 1.0.1 and earlier, specifically affecting the printthread.php component of the forum software. This issue stems from inadequate input sanitization mechanisms that fail to properly process user-supplied content before rendering it in the print view context. The vulnerability operates by allowing malicious actors to embed arbitrary web scripts or HTML code within thread messages, which then executes in the browsers of unsuspecting users who view the affected content in print mode. This particular weakness demonstrates a fundamental failure in the application's security architecture to properly validate and sanitize user inputs across all output contexts, including specialized views such as print functionality. The flaw is particularly concerning as it leverages the trust relationship between the forum software and its users, where legitimate content becomes a vector for malicious code execution.
The technical implementation of this vulnerability involves the failure to implement proper output encoding or filtering mechanisms when displaying thread content in the print view. When users create messages containing malicious script tags or HTML elements, the printthread.php script does not adequately sanitize these inputs before presenting them in the print-friendly format. This creates an environment where attackers can inject javascript code, html elements, or other malicious payloads that execute in the context of other users' browsers. The vulnerability classifies under CWE-79 as "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", specifically manifesting as a reflected XSS issue where the malicious content originates from user input and is reflected back in the print view. The attack vector requires minimal privileges since it targets the print functionality rather than requiring administrative access or authentication, making it particularly dangerous in open forum environments where any registered user can potentially exploit it.
The operational impact of this vulnerability extends beyond simple script execution to encompass potential session hijacking, credential theft, and data exfiltration capabilities. When users view affected threads in print mode, their browsers execute the injected scripts, potentially allowing attackers to steal cookies, session tokens, or other sensitive information. The vulnerability affects the entire user base that accesses the print view of compromised threads, creating a widespread attack surface. This flaw particularly impacts online communities and forums where users frequently engage with thread content, making the attack surface significant. The vulnerability's exploitation does not require special technical skills or elevated privileges, making it accessible to a broad range of threat actors. Security professionals should note that this vulnerability represents a critical weakness in the application's defensive posture, particularly in environments where forum software serves as a primary communication platform for sensitive discussions or user interactions.
Mitigation strategies for CVE-2005-4603 should prioritize immediate software updates to versions that address the input sanitization deficiencies in printthread.php. Organizations should implement comprehensive output encoding mechanisms that properly escape special characters in all user-generated content before rendering in any context, including print views. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent script execution in print contexts. Regular security audits of input validation and output encoding mechanisms should be conducted to identify similar vulnerabilities in other components. The use of web application firewalls with XSS detection capabilities can provide additional protection layers. Security teams should also implement user input monitoring and automated scanning to identify potential exploitation attempts. According to ATT&CK framework, this vulnerability maps to T1059.007 for script execution and T1566 for social engineering through malicious content delivery. Organizations should establish incident response procedures specifically addressing XSS vulnerabilities in forum software and implement regular security training for administrators to recognize and respond to such threats effectively.