CVE-2006-7031 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6.0.2900 SP2 and earlier allows remote attackers to cause a denial of service (crash) via a table element with a CSS attribute that sets the position, which triggers an "unhandled exception" in mshtml.dll.
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Analysis
by VulDB Data Team • 01/17/2025
Microsoft Internet Explorer versions 6.0.2900 and earlier contain a critical vulnerability in the mshtml.dll component that enables remote attackers to execute a denial of service attack through malformed table elements with specific CSS positioning attributes. This vulnerability stems from inadequate input validation within the browser's HTML rendering engine, specifically when processing table elements that incorporate CSS position properties. The flaw manifests when the browser encounters a table element with CSS attributes that define positioning parameters, causing the mshtml.dll module to throw an unhandled exception that results in the browser crashing and terminating the user session.
The technical implementation of this vulnerability involves the browser's parsing of HTML table structures combined with CSS styling directives that manipulate element positioning. When Internet Explorer processes a table element containing CSS attributes that set positioning properties such as absolute or relative positioning, the mshtml.dll rendering engine fails to properly handle the exception thrown during this parsing operation. This unhandled exception occurs within the core rendering component responsible for processing HTML and CSS content, effectively crashing the browser process and rendering the application unavailable to the user. The vulnerability specifically affects the mshtml.dll module which serves as the primary HTML rendering engine for Internet Explorer, making it a critical component in the attack vector.
From an operational perspective, this vulnerability presents significant risk to users of older Internet Explorer versions as it can be exploited through simple web page content without requiring any special privileges or user interaction beyond visiting a malicious website. The denial of service impact is severe as it completely disrupts the user's browsing session and may require manual browser restart to restore functionality. Attackers can craft malicious web pages containing specially formatted table elements with problematic CSS positioning attributes to trigger this vulnerability, making it particularly dangerous in environments where users frequently visit untrusted websites or where the browser is used in automated or kiosk configurations.
The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, though in this case the issue manifests as an unhandled exception rather than a simple pointer dereference. This flaw also relates to ATT&CK technique T1203 which covers exploitation of vulnerabilities for denial of service purposes, as it enables attackers to disrupt services by crashing the target application. Organizations should implement immediate mitigations including updating to supported Internet Explorer versions, applying security patches, and deploying web application firewalls to filter malicious content. Additionally, users should be educated about avoiding untrusted websites and enabling automatic security updates to prevent exploitation of this vulnerability in production environments.