CVE-2004-0479 in Internet Explorer
Summary
by MITRE
Internet Explorer 6 allows remote attackers to cause a denial of service (crash) via Javascript that creates a new popup window and disables the imagetoolbar functionality with a META tag, which triggers a null dereference.
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Analysis
by VulDB Data Team • 07/28/2025
This vulnerability exists in Internet Explorer 6 and represents a classic denial of service flaw stemming from improper handling of javascript execution within specific browser contexts. The issue manifests when malicious javascript code creates a new popup window while simultaneously disabling the imagetoolbar functionality through a META tag directive. This combination triggers a null dereference condition within the browser's javascript engine, causing the application to crash and terminate unexpectedly. The vulnerability exploits the browser's internal state management when processing popup windows in conjunction with toolbar configuration changes, creating an execution path where memory references become invalid and lead to system instability.
The technical root cause of this vulnerability aligns with CWE-476 which describes null pointer dereference conditions in software systems. When the javascript engine processes the popup creation followed by the META tag that disables imagetoolbar, it attempts to access memory locations that have either been deallocated or never properly initialized. This creates a scenario where the browser's execution context encounters a null reference that cannot be handled gracefully, resulting in an uncontrolled crash. The vulnerability operates at the intersection of browser rendering engine behavior and javascript interpretation, specifically targeting IE6's implementation of window management and toolbar functionality.
From an operational perspective, this vulnerability presents a significant risk to users of Internet Explorer 6 as it can be easily exploited through standard web browsing activities. Attackers need only craft malicious web pages containing the specific javascript and META tag combination to trigger the denial of service condition. The impact extends beyond simple browser crashes since the vulnerability can be leveraged as part of broader attack strategies, potentially disrupting user productivity and serving as a vector for more sophisticated attacks. The exploit requires no special privileges or complex setup, making it particularly dangerous in enterprise environments where IE6 might still be in use.
The attack pattern for this vulnerability follows established methodologies documented in the MITRE ATT&CK framework under techniques related to execution and privilege escalation. Specifically, the vulnerability can be categorized under the T1059.007 sub-technique for javascript execution within web browsers, and potentially under T1499 for denial of service attacks. Organizations should implement comprehensive browser security policies that mandate regular updates and discourage the use of outdated browser versions. The recommended mitigations include immediate deployment of Microsoft security patches, implementation of web application firewalls to filter malicious javascript content, and user education to avoid untrusted websites. Additionally, browser sandboxing techniques and strict content security policies can help prevent exploitation of this and similar vulnerabilities by limiting the execution scope of malicious code within the browser environment.