CVE-2006-3910 in Internet Explorer
Summary
by MITRE
Internet Explorer 6 on Windows XP SP2, when Outlook is installed, allows remote attackers to cause a denial of service (crash) by calling the NewDefaultItem function of an OVCtl (OVCtl.OVCtl.1) ActiveX object, which triggers a null dereference.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/07/2019
The vulnerability described in CVE-2006-3910 represents a critical denial of service flaw affecting Internet Explorer 6 running on Windows XP Service Pack 2 when Microsoft Outlook is installed. This issue stems from improper handling of ActiveX components within the browser environment, specifically targeting the OVCtl.OVCtl.1 ActiveX object. The flaw manifests when the browser encounters a malicious web page that triggers the NewDefaultItem function of this particular ActiveX control, leading to a system crash that disrupts normal user operations and service availability.
The technical root cause of this vulnerability lies in a null pointer dereference condition within the OVCtl ActiveX control implementation. When Internet Explorer attempts to execute the NewDefaultItem function of the OVCtl.OVCtl.1 object, the application fails to properly validate or initialize certain pointers before attempting to access them. This null dereference creates an unhandled exception that causes the browser process to terminate unexpectedly, resulting in a complete crash of the Internet Explorer application. The vulnerability is particularly concerning because it leverages the interaction between Internet Explorer and Outlook's ActiveX components, exploiting the trust relationship between these Microsoft applications. This type of flaw falls under CWE-476 which specifically addresses NULL Pointer Dereference issues in software implementations.
The operational impact of this vulnerability extends beyond simple browser crashes to potentially disrupt business operations in enterprise environments where Outlook integration is common. Users may experience unexpected browser termination while browsing legitimate websites, leading to productivity losses and potential security implications. The vulnerability is particularly dangerous in corporate settings where users frequently access web content through Internet Explorer while having Outlook installed, creating an environment where the attack vector is easily accessible. From an attacker's perspective, this represents a straightforward method for causing service disruption without requiring elevated privileges or complex exploitation techniques, making it an attractive target for malicious actors seeking to disrupt operations. The vulnerability aligns with ATT&CK technique T1499.004 which covers Network Denial of Service attacks, specifically targeting application availability through browser-based exploits.
Mitigation strategies for this vulnerability require immediate patching of affected systems through Microsoft's security updates, as the flaw exists within the core browser and ActiveX handling mechanisms. Organizations should implement browser hardening measures including disabling ActiveX controls where possible, implementing strict browser security policies, and deploying web application firewalls to filter potentially malicious content. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping systems updated. The vulnerability demonstrates the importance of proper input validation and memory management in ActiveX controls, highlighting the need for comprehensive code review processes. Organizations should also consider implementing network segmentation to limit the potential impact of such attacks and establish incident response procedures for handling browser-based denial of service events. This vulnerability underscores the critical nature of maintaining up-to-date security patches and the inherent risks associated with legacy browser environments that continue to support older ActiveX technologies.