CVE-2006-3512 in Internet Explorer
Summary
by MITRE
Internet Explorer 6 on Windows XP allows remote attackers to cause a denial of service (crash) by setting the Enabled property of a DXTFilter ActiveX object to true, which triggers a null dereference.
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Analysis
by VulDB Data Team • 07/12/2021
The vulnerability identified as CVE-2006-3512 represents a critical denial of service flaw in Internet Explorer 6 running on Windows XP systems. This issue specifically targets the DXTFilter ActiveX control, which is part of Microsoft's multimedia framework designed for video processing and filtering operations. The vulnerability arises from improper handling of the Enabled property within the ActiveX object, creating a condition where a null pointer dereference occurs when the property is set to true. This type of memory access violation fundamentally compromises the stability of the affected application.
The technical exploitation of this vulnerability occurs through the manipulation of ActiveX controls within web browser contexts, leveraging the inherent trust model that browsers maintain with locally installed components. When an attacker crafts a malicious web page that instantiates a DXTFilter ActiveX object and sets its Enabled property to true, the browser's processing of this command triggers a null pointer dereference within the ActiveX control's memory management routines. This memory access violation causes Internet Explorer to crash and terminate unexpectedly, resulting in a denial of service condition that prevents legitimate users from accessing the affected system. The vulnerability specifically aligns with CWE-476, which categorizes null pointer dereference issues as a fundamental programming error that leads to application instability and potential system compromise.
From an operational perspective, this vulnerability poses significant risks to enterprise environments where Internet Explorer 6 remains in use, particularly in legacy systems that have not been properly migrated to supported browser versions. The remote nature of the attack means that users can be compromised simply by visiting malicious websites, making this vector particularly dangerous in corporate networks where users may not be security-aware. The vulnerability can be exploited through various attack scenarios including phishing campaigns, compromised websites, or malicious advertisements that automatically trigger the malicious ActiveX object instantiation. The impact extends beyond individual user sessions to potentially disrupt business operations, as users may lose access to critical web-based applications and services that require browser functionality.
The mitigation strategies for this vulnerability should prioritize immediate patching of affected systems through Microsoft's security updates, as the company released specific fixes for Internet Explorer 6 that address the ActiveX control memory management issues. Organizations should also implement browser hardening measures including ActiveX control restrictions, browser security policies, and the deployment of web application firewalls to prevent access to potentially malicious content. Network-level protections such as content filtering and intrusion prevention systems can help detect and block exploitation attempts. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping browser software updated. The vulnerability demonstrates the importance of proper memory management practices in software development and highlights the risks associated with legacy browser support, particularly in environments where security updates are not regularly applied. This case study exemplifies how seemingly minor programming errors in ActiveX controls can result in significant security implications, as outlined in the ATT&CK framework's techniques for privilege escalation and denial of service through application-level vulnerabilities.