CVE-2000-0329 in Internet Explorer
Summary
by MITRE
A Microsoft ActiveX control allows a remote attacker to execute a malicious cabinet file via an attachment and an embedded script in an HTML mail, aka the "Active Setup Control" vulnerability.
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Analysis
by VulDB Data Team • 05/31/2025
The CVE-2000-0329 vulnerability represents a critical security flaw in Microsoft Windows operating systems that leveraged ActiveX controls to execute malicious code remotely. This vulnerability specifically targeted the Active Setup functionality within Windows, which is designed to automatically configure software components upon installation or update. The flaw occurred when a malicious ActiveX control was embedded within an HTML email attachment, allowing attackers to bypass traditional security measures and execute arbitrary code on vulnerable systems. The vulnerability exploited the trust relationship between Windows and ActiveX controls, enabling attackers to install and run malicious cabinet files without user interaction or explicit consent.
The technical implementation of this vulnerability relied on the improper handling of ActiveX control registration and execution within Internet Explorer and other Microsoft applications that supported ActiveX. When a user opened an email containing the malicious HTML attachment, the embedded script would automatically trigger the ActiveX control, which would then download and execute a cabinet file from a remote server. This cabinet file typically contained malicious executables or additional malware components that would install themselves on the victim's system. The vulnerability was particularly dangerous because it could be exploited through simple email attachments without requiring any special privileges or user interaction beyond opening the email. The flaw existed in the way Windows processed Active Setup instructions and handled ActiveX control initialization, creating a path for attackers to execute code with the privileges of the logged-in user.
The operational impact of CVE-2000-0329 was severe and widespread, affecting numerous versions of Microsoft Windows including Windows 95, 98, ME, NT 4.0, and 2000. Attackers could leverage this vulnerability to gain unauthorized access to systems, install backdoors, steal sensitive information, or deploy additional malware. The vulnerability was particularly effective in corporate environments where email was the primary communication method and users often opened attachments without considering security implications. The attack vector required minimal technical expertise from attackers, making it a popular choice for automated malware distribution campaigns. Systems with default Windows configurations were particularly vulnerable, as the ActiveX controls were enabled by default and no additional security prompts were displayed during execution. This vulnerability contributed significantly to the rapid spread of worms and malware during the early 2000s, as it allowed attackers to compromise systems without requiring user interaction or specialized knowledge of system vulnerabilities.
Microsoft addressed this vulnerability through the release of security patches and updates that modified how ActiveX controls were processed and how Active Setup instructions were executed. The recommended mitigations included disabling ActiveX controls in web browsers, implementing proper email filtering and security policies, and ensuring that systems were updated with the latest security patches. Organizations were advised to configure their email servers to scan for and block malicious HTML attachments, particularly those containing embedded ActiveX controls. The vulnerability highlighted the importance of proper input validation and the risks associated with trusting unverified code execution within operating system components. Security professionals recommended implementing network segmentation and monitoring for suspicious ActiveX control usage patterns. This vulnerability also contributed to the development of more robust security models in subsequent Microsoft products and influenced the broader industry's approach to handling ActiveX controls and embedded scripting languages. The incident demonstrated the critical importance of timely patch management and user education in preventing widespread exploitation of such vulnerabilities. The flaw was categorized under CWE-94 as an "Improper Control of Generation of Code ('Code Injection')" and aligned with ATT&CK techniques involving execution through ActiveX controls and malicious file execution.