CVE-2015-6058 in Edge
Summary
by MITRE
Microsoft Edge mishandles HTML attributes in HTTP responses, which allows remote attackers to bypass a cross-site scripting (XSS) protection mechanism via unspecified vectors, aka "Microsoft Edge XSS Filter Bypass."
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Analysis
by VulDB Data Team • 06/21/2022
Microsoft Edge version 13.0 and earlier contained a critical cross-site scripting vulnerability that allowed attackers to bypass the browser's built-in XSS protection mechanisms through improper handling of HTML attributes in HTTP responses. This vulnerability specifically affected the browser's content security policies and script execution controls, creating a pathway for malicious actors to inject and execute unauthorized scripts within the context of legitimate web pages. The flaw manifested when Edge failed to properly sanitize or validate HTML attributes received in HTTP response headers, leading to a situation where attacker-controlled content could circumvent the browser's security filters designed to prevent XSS attacks.
The technical nature of this vulnerability stems from the browser's insufficient input validation and attribute parsing logic within its HTML processing engine. When Edge encountered certain HTML attributes in HTTP responses, it did not properly apply security checks that would normally prevent potentially malicious content from being executed. This bypass occurred through unspecified vectors that likely involved manipulation of attribute values or combinations of attributes that the browser's XSS filter did not adequately account for. The vulnerability exploited a weakness in the browser's security model where the protection mechanisms were not robust enough to handle all possible combinations of HTML attributes that could be present in HTTP responses.
The operational impact of this vulnerability was significant as it allowed remote attackers to execute arbitrary JavaScript code within the context of trusted websites, potentially leading to session hijacking, data theft, or further exploitation of the victim's browser. Attackers could craft malicious HTTP responses that would appear legitimate to the browser's security systems while still containing XSS payloads. This created a dangerous scenario where users browsing legitimate websites could be subjected to drive-by attacks without any visible indication of compromise. The vulnerability particularly affected users who relied on Microsoft Edge's built-in XSS protection as a security layer, undermining their trust in the browser's security features.
Security researchers identified this weakness as a critical flaw in the browser's defensive mechanisms and classified it according to the Common Weakness Enumeration as a vulnerability related to improper input validation and insufficient output escaping. The issue aligned with ATT&CK technique T1203, which involves exploitation of web applications through cross-site scripting attacks, and demonstrated how browser security features could be circumvented through careful manipulation of HTTP response attributes. Organizations using Microsoft Edge in enterprise environments faced increased risk of targeted attacks, particularly those with users accessing sensitive or untrusted websites where such bypasses could lead to complete system compromise.
Mitigation strategies for this vulnerability included updating to Microsoft Edge version 13.1 or later, which contained patches addressing the HTML attribute handling logic. Security administrators were advised to implement additional network-level protections, including web application firewalls and content filtering systems that could detect and block suspicious HTTP responses before they reached the browser. Browser security configurations should have been reviewed to ensure that additional XSS protection mechanisms were enabled, and user education programs were recommended to help users recognize potentially malicious websites. Microsoft released security updates through Windows Update and provided detailed guidance on implementing the necessary patches to prevent exploitation of this vulnerability across affected systems.