CVE-2014-6365 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 8 through 11 allows remote attackers to bypass the XSS filter via a crafted attribute of an element in an HTML document, aka "Internet Explorer XSS Filter Bypass Vulnerability," a different vulnerability than CVE-2014-6328.
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Analysis
by VulDB Data Team • 07/01/2024
Microsoft Internet Explorer versions 8 through 11 contained a critical cross-site scripting vulnerability that allowed remote attackers to circumvent the built-in XSS filter mechanisms through the manipulation of HTML element attributes. This vulnerability specifically exploited weaknesses in how the browser's security filters processed certain attribute values, enabling attackers to inject malicious scripts that would execute in the context of the victim's browser session. The flaw represented a significant bypass of the browser's security model, as it allowed attackers to evade the protection mechanisms designed to prevent common XSS attack vectors. The vulnerability was particularly dangerous because it affected multiple versions of Internet Explorer, creating a widespread attack surface across numerous enterprise environments where older browser versions remained in use. According to CWE classification, this represents a weakness in the input validation and output encoding mechanisms that should have prevented the execution of malicious code. The attack vector involved crafting specific HTML attributes that would be interpreted by the browser in a way that bypassed the XSS filter's detection algorithms. This allowed attackers to inject script code that would execute when users viewed malicious web pages, potentially leading to session hijacking, credential theft, or further exploitation of the victim's system. The vulnerability's impact was amplified by the widespread adoption of Internet Explorer in corporate environments, where users often had elevated privileges and access to sensitive internal resources.
The technical implementation of this XSS bypass leveraged specific parsing behaviors within Internet Explorer's HTML parser that failed to properly sanitize attribute values before rendering them in the browser context. Attackers could craft HTML elements with carefully constructed attributes that would be processed by the browser's XSS filter in a manner that allowed malicious content to slip through the security checks. The vulnerability exploited the gap between how the filter was designed to detect and block XSS attempts and how the actual HTML parsing and rendering occurred in the browser's engine. This discrepancy created a scenario where legitimate security protections were effectively neutralized by specific attribute constructions that the filter did not properly account for. The bypass mechanism was particularly sophisticated because it required understanding of the browser's internal parsing logic and the specific conditions under which the XSS filter would fail to properly sanitize input. Security researchers identified that the vulnerability was related to how the browser's security policies were applied during HTML document processing, specifically in the context of attribute handling within element tags. This issue was distinct from other related vulnerabilities such as CVE-2014-6328, indicating a separate code path and attack surface that required different mitigation approaches.
The operational impact of this vulnerability extended beyond simple script execution to encompass potential privilege escalation and data exfiltration scenarios. Organizations running affected versions of Internet Explorer faced significant risks as attackers could leverage this vulnerability to gain unauthorized access to user sessions and potentially compromise entire corporate networks. The vulnerability's persistence across multiple IE versions meant that even organizations that had upgraded to newer versions still remained at risk if users continued to access websites through older browser versions. This created a complex security management challenge where organizations had to account for legacy browser usage patterns while implementing broader security controls. The vulnerability was particularly concerning in enterprise environments where users had access to sensitive systems and data, as successful exploitation could lead to unauthorized access to corporate resources. The attack could be delivered through various means including malicious websites, email attachments, or compromised web applications, making it difficult to defend against through traditional perimeter security measures. Organizations needed to implement layered security approaches that included browser hardening, network-based filtering, and user education to mitigate the risks associated with this vulnerability.
Mitigation strategies for this vulnerability focused on both immediate remediation and long-term security improvements. The primary recommendation was to upgrade to supported versions of Internet Explorer or migrate to modern browsers that had addressed this specific vulnerability. Microsoft released security updates that corrected the XSS filter bypass mechanisms, but organizations needed to ensure these updates were deployed across all affected systems. Browser hardening configurations were essential, including disabling unnecessary features and implementing stricter security policies that would reduce the attack surface available to potential attackers. Network-based security controls such as web application firewalls and content filtering systems could provide additional protection layers that would detect and block malicious payloads even if the browser's built-in protections were bypassed. Security awareness training for users became critical as many attacks leveraging this vulnerability would require user interaction with malicious content, making human factors a significant consideration in overall security posture. Organizations implementing security controls should have followed ATT&CK framework recommendations for defending against browser-based attacks, including monitoring for suspicious attribute usage patterns and implementing proper input validation at multiple layers of the application stack. The vulnerability highlighted the importance of maintaining up-to-date security patches and the need for comprehensive security testing that included evaluation of browser security features against known attack patterns.