CVE-2008-4800 in Debug Diagnostic Tool
Summary
by MITRE
The DebugDiag ActiveX control in CrashHangExt.dll, possibly 1.0, in Microsoft Debug Diagnostic Tool allows remote attackers to cause a denial of service (NULL pointer dereference and Internet Explorer 6.0 crash) via a large negative integer argument to the GetEntryPointForThread method. NOTE: this issue might only be exploitable in limited environments or non-default browser settings.
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Analysis
by VulDB Data Team • 08/02/2021
The CVE-2008-4800 vulnerability represents a critical denial of service flaw within Microsoft's Debug Diagnostic Tool, specifically affecting the CrashHangExt.dll ActiveX control version 1.0. This vulnerability exists in the DebugDiag tool's handling of the GetEntryPointForThread method, which processes integer arguments that can trigger unexpected behavior when malformed input is provided. The vulnerability operates through a NULL pointer dereference condition that ultimately leads to a complete Internet Explorer 6.0 crash, effectively rendering the browser unusable for the targeted user. The flaw demonstrates the inherent risks associated with ActiveX control implementations in web browsers, where client-side components can be manipulated to execute unintended code paths that result in system instability.
The technical exploitation of this vulnerability requires an attacker to craft a malicious web page that invokes the vulnerable ActiveX control with a large negative integer argument. When the GetEntryPointForThread method processes this malformed input, it fails to properly validate the argument before attempting to dereference a pointer that remains NULL, resulting in an immediate system crash. This type of vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference conditions, and demonstrates how improper input validation can lead to complete system failure. The attack vector leverages the browser's ActiveX plugin architecture, where the malicious payload is delivered through a webpage that automatically loads the vulnerable component, making it particularly dangerous in environments where users may encounter such content without proper security awareness.
The operational impact of CVE-2008-4800 extends beyond simple denial of service, as it represents a potential entry point for more sophisticated attacks within compromised environments. While the vulnerability primarily causes browser crashes, the underlying NULL pointer dereference condition could potentially be leveraged in combination with other exploits to achieve arbitrary code execution or privilege escalation. The limited exploitability mentioned in the original description suggests that the vulnerability may be environment-dependent, potentially requiring specific browser configurations or security settings to be effective. This characteristic places the vulnerability in the ATT&CK framework under the T1203 - Exploitation for Client Execution tactic, where adversaries leverage client-side exploits to gain initial access or extend their compromise.
Mitigation strategies for CVE-2008-4800 should focus on both immediate remediation and long-term security hardening. The most effective immediate solution involves disabling ActiveX controls in Internet Explorer or implementing proper security zones that restrict ActiveX loading from untrusted sources. Organizations should also consider deploying application whitelisting solutions that prevent execution of the vulnerable CrashHangExt.dll component. The vulnerability highlights the importance of keeping diagnostic and development tools updated, as Microsoft likely addressed this issue in subsequent releases of the Debug Diagnostic Tool. Additionally, network-level protections such as content filtering and web application firewalls can help prevent users from accessing malicious pages that contain the exploit. From a defensive perspective, this vulnerability underscores the necessity of implementing comprehensive browser security policies and regular security assessments to identify and remediate similar ActiveX-based vulnerabilities that could be exploited in targeted attacks.