CVE-2006-3640 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 5.01 and 6 allows certain script to persist across navigations between pages, which allows remote attackers to obtain the window location of visited web pages in other domains or zones, aka "Window Location Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 07/13/2021
This vulnerability exists in Microsoft Internet Explorer versions 5.01 and 6, representing a significant information disclosure flaw that exploits cross-domain navigation behavior. The vulnerability stems from how Internet Explorer handles script persistence across page navigations, specifically allowing malicious code to access window location information from visited web pages in different domains or security zones. This represents a classic case of insufficient security boundary enforcement between different trust levels within the browser environment.
The technical flaw manifests through the improper handling of window.location objects when users navigate between different web pages. When a user visits multiple pages across different domains or security zones, the script execution context should maintain strict isolation to prevent information leakage. However, this vulnerability allows remote attackers to craft malicious scripts that can access the window.location properties of previously visited pages, effectively enabling them to discover the URLs of visited sites. This cross-domain information leakage occurs because the browser fails to properly enforce security boundaries when scripts attempt to access location information across navigation boundaries.
The operational impact of this vulnerability is substantial as it enables attackers to perform passive reconnaissance of user browsing history without direct user interaction. Attackers can construct malicious web pages that, when visited, can extract the window.location information from other domains, potentially revealing sensitive navigation patterns, visited websites, or even specific URLs that might contain confidential information. This vulnerability particularly affects users who browse multiple domains or zones, as it can expose their browsing behavior and potentially reveal access patterns to sensitive resources or services.
This vulnerability maps to CWE-200, which describes "Information Exposure," and specifically relates to information disclosure through improper access control mechanisms. The flaw also connects to ATT&CK technique T1056.001, "Input Injection: Data Encoding," as attackers can exploit the scripting environment to inject malicious code that leverages the browser's navigation handling. The vulnerability demonstrates a failure in the browser's security model where the principle of least privilege is violated, allowing scripts from one domain to access location information from another domain without proper authorization.
Mitigation strategies should focus on implementing proper cross-domain security controls and ensuring that window.location objects are properly isolated between different navigation contexts. Users should be encouraged to keep their browsers updated with the latest security patches, as Microsoft released fixes for this vulnerability in subsequent updates. Organizations should consider implementing additional security measures such as content security policies, proper zone configuration, and regular security assessments of browser environments to prevent exploitation of such information disclosure vulnerabilities. The vulnerability also highlights the importance of maintaining strict isolation between different security zones within web browsers and proper enforcement of domain-based security boundaries.