CVE-2009-3003 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 through 8 allows remote attackers to spoof the address bar, via window.open with a relative URI, to show an arbitrary URL on the web site visited by the victim, as demonstrated by a visit to an attacker-controlled web page, which triggers a spoofed login form for the site containing that page.
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Analysis
by VulDB Data Team • 08/20/2021
Microsoft Internet Explorer versions 6 through 8 contain a critical security vulnerability that enables remote attackers to perform address bar spoofing through improper handling of window.open() function with relative URIs. This flaw resides in the browser's navigation and URL display mechanisms, where the application fails to properly validate or sanitize URI references when creating new windows or tabs. The vulnerability specifically manifests when an attacker crafts a malicious web page that utilizes the window.open() API with a relative URI parameter that points to a different domain or subdomain than the current page. When a victim visits this malicious page and interacts with the spoofed navigation element, the browser displays a falsified address bar that shows the attacker-controlled URL instead of the actual destination. This deceptive behavior exploits the browser's trust model and can be leveraged to create convincing phishing attacks where victims believe they are visiting legitimate websites while actually being directed to malicious endpoints.
The technical exploitation of this vulnerability involves crafting HTML content that invokes window.open() with carefully constructed relative URI parameters that manipulate the browser's address bar display. Attackers can leverage this flaw to present a fake login form or other malicious content while displaying a legitimate domain name in the address bar, effectively bypassing user security awareness and browser security indicators. The vulnerability is particularly dangerous because it operates at the user interface level, making it difficult for victims to distinguish between legitimate and malicious content based on address bar information alone. This issue represents a classic case of insufficient input validation and improper URI handling, aligning with CWE-601 and CWE-79 vulnerabilities that relate to URL redirection and cross-site scripting flaws. The flaw essentially allows for a form of UI redressing or clickjacking where the visual representation of the browser's navigation context is manipulated to deceive users.
The operational impact of CVE-2009-3003 extends beyond simple phishing attacks to potentially enable more sophisticated social engineering campaigns that can compromise user credentials, steal sensitive information, or redirect users to malicious sites. Victims may unknowingly enter login credentials or personal information into forms that appear to be from legitimate services but are actually controlled by attackers. The vulnerability affects a wide range of Internet Explorer versions, making it particularly dangerous as many organizations were still using these older browser versions in 2009. Attackers can exploit this vulnerability to create convincing fake banking or social media login pages that display legitimate domain names in the address bar, thereby bypassing user security awareness and browser security features. This flaw significantly undermines the trust model that users place in browser address bar information and can lead to widespread credential theft and data breaches across affected organizations.
Organizations and users should immediately implement mitigations including browser updates to newer versions of Internet Explorer that have addressed this vulnerability, along with enhanced security awareness training to help users recognize potential spoofing attempts. Network administrators should consider implementing web application firewalls and content filtering solutions that can detect and block malicious window.open() usage patterns. Users should be educated about the importance of verifying address bar information, especially when entering sensitive data, and should be trained to look for other security indicators beyond URL display. The vulnerability highlights the importance of proper input validation and URI handling in web browsers, emphasizing the need for robust security controls at multiple layers of the application stack. Additionally, organizations should consider implementing browser security policies that restrict the use of potentially dangerous JavaScript APIs and ensure that all systems are regularly updated with the latest security patches to prevent exploitation of known vulnerabilities. This vulnerability demonstrates the critical importance of maintaining up-to-date browser software and implementing comprehensive security measures to protect against UI spoofing attacks that can bypass traditional security controls.