CVE-2006-3471 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 on Windows XP allows remote attackers to cause a denial of service (crash) via a table with a frameset as a child, which triggers a null dereference, as demonstrated using the appendChild method.
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Analysis
by VulDB Data Team • 05/02/2019
Microsoft Internet Explorer 6 running on Windows XP contains a critical vulnerability that manifests as a null pointer dereference when processing malformed HTML content. This vulnerability specifically occurs when the browser encounters a table element that contains a frameset as a child element, triggering an improper memory access condition that leads to application crash and denial of service. The flaw is particularly exploitable through the appendChild JavaScript method, which allows remote attackers to construct malicious HTML payloads that can be delivered via web pages or email attachments. The vulnerability resides in the browser's HTML parsing and rendering engine, where the absence of proper input validation and memory management leads to the dereferencing of null pointers during the processing of nested table and frameset structures. This issue represents a classic example of improper handling of malformed input data, which aligns with CWE-476, null pointer dereference, and demonstrates how web browser vendors must implement robust input sanitization and memory protection mechanisms to prevent such exploitation scenarios. The attack vector is particularly dangerous because it can be initiated through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a malicious webpage. The operational impact of this vulnerability extends beyond simple service disruption as it can be leveraged by attackers to create persistent denial of service conditions against targeted systems, potentially leading to system instability and reduced availability of critical services. This vulnerability directly impacts the browser's ability to maintain stable operation when processing HTML content and represents a fundamental flaw in the browser's memory management and input validation procedures. The issue is particularly concerning in enterprise environments where Internet Explorer 6 remains in use, as it provides attackers with a reliable method to disrupt normal business operations and potentially gain further access to compromised systems. Organizations should implement immediate mitigations including browser updates, network-based filtering to block malicious content, and user education to avoid visiting untrusted websites. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that include web application firewalls, content filtering solutions, and regular security assessments to identify and remediate similar memory corruption vulnerabilities. From an attacker perspective, this vulnerability maps to techniques described in the attack pattern taxonomy under the category of memory corruption exploits, specifically targeting browser rendering engines through malformed HTML content. The technical implementation of this attack requires minimal sophistication and can be automated, making it particularly dangerous for widespread deployment. The vulnerability's exploitation aligns with the broader threat landscape where browser-based attacks continue to represent one of the most prevalent attack vectors in enterprise security, emphasizing the critical need for continuous monitoring and rapid response to emerging threats in web browser environments. Security professionals should prioritize the remediation of this vulnerability through patch management processes and consider implementing additional security controls such as browser hardening configurations, sandboxing mechanisms, and network segmentation to limit the potential impact of such attacks.