CVE-2018-10678 in MyBB
Summary
by MITRE
MyBB 1.8.15, when accessed with Microsoft Edge, mishandles 'target="_blank" rel="noopener"' in A elements, which makes it easier for remote attackers to conduct redirection attacks.
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Analysis
by VulDB Data Team • 02/04/2020
This vulnerability exists in MyBB version 1.8.15 where the software fails to properly sanitize or validate hyperlink attributes when rendering content in Microsoft Edge browser environments. The issue specifically concerns how the platform processes anchor elements with target="_blank" and rel="noopener" attributes, which are standard security measures designed to prevent malicious redirection attacks. When these attributes are present in user-generated content or forum posts, the application does not adequately process them, potentially allowing attackers to craft links that bypass intended security controls. The vulnerability represents a classic case of insufficient input validation and output encoding, where the application fails to properly handle potentially dangerous HTML attributes that could be exploited to redirect users to malicious websites. This flaw particularly affects Microsoft Edge browsers due to how they interpret these specific attribute combinations, making the attack vector more relevant in that particular environment.
The technical exploitation of this vulnerability relies on the browser's handling of the rel="noopener" attribute which is designed to prevent the new page from accessing the window.opener property and potentially redirecting the original page. When MyBB fails to properly process this attribute, attackers can craft malicious links that appear legitimate but actually redirect users to phishing sites or sites hosting malware. The vulnerability stems from improper HTML sanitization routines that do not adequately filter or neutralize dangerous attribute combinations, allowing malicious content to persist in the application's output. This type of vulnerability falls under CWE-79 which addresses Cross-Site Scripting (XSS) issues, specifically related to insufficient output escaping and improper handling of HTML attributes. The flaw essentially creates a bypass mechanism for standard security protections that should prevent malicious redirection attacks through compromised forum content.
The operational impact of this vulnerability extends beyond simple redirection attacks as it can enable more sophisticated phishing campaigns and social engineering attacks within forum environments. Attackers can exploit this weakness to direct forum users to malicious websites that mimic legitimate services, potentially stealing credentials or installing malware. The vulnerability is particularly dangerous in community forum settings where users trust the platform and its content, making them more susceptible to falling for these redirection attacks. Since MyBB is commonly used for discussion forums, bulletin boards, and community platforms, the potential attack surface is significant. The vulnerability can be leveraged by attackers to compromise user sessions, harvest sensitive information, or spread malware throughout the affected community. This represents a serious security concern as it undermines the trust users place in the platform's security mechanisms and can lead to widespread compromise of user accounts and data.
Organizations and administrators should immediately update their MyBB installations to versions that address this vulnerability, as the fix typically involves proper HTML attribute sanitization and validation routines. The recommended mitigation includes implementing robust input validation that properly handles target="_blank" and rel="noopener" attributes, ensuring that these security measures are not bypassed. System administrators should also consider implementing additional monitoring for suspicious link patterns within forum content and establishing content filtering rules that can detect and block potentially malicious attribute combinations. Organizations should follow security best practices outlined in the OWASP Top Ten and implement proper HTML sanitization libraries that properly handle these security attributes. The vulnerability demonstrates the importance of browser-specific security considerations and the need for comprehensive security testing across different browser environments. Additionally, implementing proper security headers and Content Security Policy (CSP) configurations can provide additional defense-in-depth measures against similar redirection attacks. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar issues that may exist in other HTML processing components of the application.