CVE-2008-1086 in Windows
Summary
by MITRE
The HxTocCtrl ActiveX control (hxvz.dll), as used in Microsoft Internet Explorer 5.01 SP4 and 6 SP1, in Windows XP SP2, Server 2003 SP1 and SP2, Vista SP1, and Server 2008, allows remote attackers to execute arbitrary code via malformed arguments, which triggers memory corruption.
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Analysis
by VulDB Data Team • 06/01/2025
The vulnerability identified as CVE-2008-1086 represents a critical heap-based buffer overflow in the HxTocCtrl ActiveX control component. This flaw exists within the hxvz.dll library that is integrated into Microsoft Internet Explorer versions 5.01 SP4 and 6 SP1 across multiple Windows operating systems including Windows XP SP2, Server 2003 SP1 and SP2, Vista SP1, and Server 2008. The vulnerability stems from insufficient input validation within the ActiveX control's argument processing mechanism, creating a condition where malformed parameters can trigger memory corruption. This type of vulnerability falls under CWE-121, heap-based buffer overflow, which is classified as a serious software security weakness that can lead to arbitrary code execution.
The technical exploitation of this vulnerability occurs when a malicious web page loads the vulnerable HxTocCtrl ActiveX control and passes malformed arguments to the control's methods. The insufficient bounds checking in the hxvz.dll component allows an attacker to overwrite adjacent memory locations, potentially leading to stack corruption or heap corruption depending on the specific memory layout at runtime. When the control processes these malformed arguments, the buffer overflow can result in execution of arbitrary code within the context of the user running Internet Explorer. This represents a classic remote code execution vulnerability that leverages the trust model inherent in ActiveX controls, where browser components are allowed to execute with elevated privileges. The vulnerability is particularly concerning because it affects multiple versions of Internet Explorer across different Windows operating systems, making it a widespread threat vector.
The operational impact of CVE-2008-1086 extends beyond simple code execution as it provides attackers with a method to bypass security boundaries and potentially gain full system compromise. When successfully exploited, the vulnerability allows remote attackers to execute malicious code with the privileges of the logged-in user, which could lead to complete system takeover, data exfiltration, or deployment of additional malware. The attack surface is broad since the vulnerable ActiveX control is present in multiple Internet Explorer versions across various Windows platforms, meaning that attackers can target a wide range of systems without requiring specific system information. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1195.002 for the use of malicious ActiveX controls, and represents a common vector for initial access and privilege escalation in enterprise environments where legacy Internet Explorer installations persist.
Mitigation strategies for CVE-2008-1086 should focus on both immediate remediation and long-term security hardening. The most effective immediate solution involves disabling the vulnerable HxTocCtrl ActiveX control through registry modifications or group policy settings, preventing automatic loading of the component. Microsoft released security updates that patched this vulnerability, and organizations should ensure all affected systems receive these patches promptly. Additionally, implementing security measures such as Internet Explorer's Protected Mode, disabling ActiveX controls in untrusted zones, and employing application whitelisting can significantly reduce the risk of exploitation. Network-level protections including web application firewalls and content filtering solutions can help detect and block malicious payloads attempting to exploit this vulnerability. The remediation approach should also include comprehensive vulnerability scanning to identify systems running vulnerable versions of Internet Explorer and the affected ActiveX control, followed by proper patch management and user education regarding safe browsing practices to prevent accidental exploitation through malicious websites.