CVE-2004-0843 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.5 and 6 does not properly handle plug-in navigation, which allows remote attackers to alter displayed address bars and thereby spoof web pages, facilitating phishing attacks, aka the "Plug-in Navigation Address Bar Spoofing Vulnerability."
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Analysis
by VulDB Data Team • 01/02/2025
The vulnerability identified as CVE-2004-0843 represents a critical security flaw in Microsoft Internet Explorer versions 5.5 and 6 that specifically targets the browser's handling of plugin navigation components. This issue stems from the browser's improper management of how address bar information is displayed during plugin interactions, creating a fundamental weakness in the user interface's ability to maintain accurate navigation context. The flaw occurs when Internet Explorer processes navigation requests through various plugin mechanisms, particularly affecting ActiveX controls and other embedded objects that interact with the browser's navigation system.
The technical implementation of this vulnerability allows malicious actors to manipulate the address bar content displayed to users during plugin navigation events. When a user encounters a web page containing malicious plugins, the attacker can exploit this flaw to cause the browser to display a false address bar that appears to show a legitimate website URL while actually directing users to a fraudulent destination. This manipulation occurs because Internet Explorer fails to properly validate or sanitize the navigation context when plugins attempt to modify the displayed address information. The vulnerability specifically affects how the browser handles the relationship between plugin execution and address bar updates, creating a window where spoofing can occur without proper user verification mechanisms.
The operational impact of this vulnerability extends far beyond simple visual deception, as it directly enables sophisticated phishing attacks that can bypass user security awareness and traditional browser protections. Attackers can craft malicious web pages that appear to display legitimate banking or e-commerce sites while actually redirecting users to counterfeit domains designed to harvest credentials and sensitive information. This vulnerability represents a significant threat to online security because it exploits the fundamental trust users place in address bar information, which serves as a primary indicator of website authenticity. The attack vector is particularly dangerous because it can be executed through standard web browsing activities without requiring special privileges or complex exploitation techniques, making it accessible to attackers with minimal technical expertise.
Security researchers have categorized this vulnerability under CWE-200, which addresses "Information Exposure Through Output with Sensitive Information," and it aligns with ATT&CK technique T1566.001, "Phishing: Spearphishing Attachment," as it enables the creation of highly convincing phishing pages. The vulnerability's impact is further amplified by its compatibility with the widespread Internet Explorer user base of that era, making it particularly dangerous for organizations and individuals who had not yet migrated to more secure browser alternatives. Mitigation strategies include applying Microsoft security patches, disabling plugin functionality where possible, implementing browser security policies that restrict plugin behavior, and educating users about the importance of verifying address bar information even when it appears legitimate. Additionally, network administrators should consider implementing web content filtering solutions that can detect and block suspicious navigation patterns associated with this vulnerability. The remediation process requires careful attention to ensure that security updates do not disrupt legitimate business applications that depend on plugin functionality, while also recognizing that the fundamental flaw in the browser's navigation handling mechanism necessitates complete patching rather than partial workarounds.