CVE-2004-2219 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 allows remote attackers to spoof the address bar to facilitate phishing attacks via Javascript that uses an invalid URI, modifies the Location field, then uses history.back to navigate to the previous domain, aka NullyFake.
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Analysis
by VulDB Data Team • 05/07/2019
This vulnerability exists in Microsoft Internet Explorer 6 and represents a sophisticated phishing attack vector that exploits the browser's handling of URI validation and navigation history. The flaw allows malicious actors to manipulate the address bar display to appear as though users are visiting legitimate websites while actually directing them to malicious content. The attack specifically leverages javascript code that creates an invalid uri, modifies the location field, and then uses the history.back function to navigate to a previous domain, effectively creating a false impression of security and legitimacy.
The technical implementation of this vulnerability stems from how Internet Explorer 6 processes and displays URI information within the address bar. When a malicious script executes an invalid uri and subsequently modifies the location field, the browser's navigation history system fails to properly validate or update the displayed address. This creates a window where users see a legitimate-looking address bar while the actual content being served comes from a different domain. The vulnerability operates at the intersection of browser security model weaknesses and javascript execution capabilities, making it particularly dangerous for users who rely on address bar verification for security assessment.
The operational impact of this vulnerability is significant within the context of phishing attacks and social engineering campaigns. Attackers can exploit this flaw to create convincing fake login pages or fraudulent websites that appear legitimate to users. The technique effectively bypasses user security awareness by making the address bar display incorrect information while maintaining the actual navigation to malicious sites. This vulnerability demonstrates how browser implementation details can create security gaps that adversaries can leverage for financial fraud, credential theft, and other malicious activities.
This vulnerability aligns with CWE-601 and CWE-1021 categories, specifically addressing open redirect vulnerabilities and insecure direct object references. It also maps to several ATT&CK techniques including T1566 for phishing attacks and T1071 for application layer protocols. The attack vector operates through the web browser's javascript engine and navigation system, making it particularly effective against users who trust address bar information as a security indicator. The NullyFake moniker reflects the technique's ability to create "null" or fake address bar displays that mislead users into believing they are on legitimate sites.
Mitigation strategies for this vulnerability include implementing proper URI validation in browser implementations, enhancing address bar display mechanisms to prevent manipulation, and deploying javascript security restrictions that limit the ability to modify navigation history. Users should be educated about the limitations of address bar verification and encouraged to verify website legitimacy through multiple means. Browser vendors should implement more robust validation of URI information and navigation history updates to prevent malicious scripts from manipulating displayed address information. Additionally, security patches and updates that address the underlying browser navigation and URI handling mechanisms are essential for protecting against this specific class of phishing attacks.