CVE-2002-0647 in Internet Explorer
Summary
by MITRE
Buffer overflow in a legacy ActiveX control used to display specially formatted text in Microsoft Internet Explorer 5.01, 5.5, and 6.0 allows remote attackers to execute arbitrary code, aka "Buffer Overrun in Legacy Text Formatting ActiveX Control".
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Analysis
by VulDB Data Team • 06/22/2025
This vulnerability resides in a legacy ActiveX control component that was historically used by Microsoft Internet Explorer versions 5.01, 5.5, and 6.0 for rendering specially formatted text content. The flaw manifests as a classic buffer overrun condition within the text formatting functionality of this ActiveX control, which operates outside the typical browser security boundaries. The vulnerability stems from insufficient input validation and bounds checking when processing text data that exceeds the allocated buffer space, creating an exploitable condition that can be triggered through maliciously crafted web content. This represents a fundamental security weakness in the control's implementation that directly violates secure coding principles and industry best practices.
The technical exploitation of this vulnerability occurs when a user visits a malicious web page that contains specially crafted text formatting data designed to overflow the buffer allocated within the ActiveX control. The buffer overrun allows an attacker to overwrite adjacent memory locations, potentially including the instruction pointer or other critical program variables, enabling arbitrary code execution with the privileges of the user running the vulnerable browser. This type of vulnerability maps directly to CWE-121, which describes buffer overflow conditions in stack-based buffers, and more specifically to CWE-787, which addresses out-of-bounds write operations. The attack vector is particularly dangerous because it leverages the trust relationship between the browser and ActiveX controls, allowing remote code execution without requiring local system access.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a mechanism to bypass standard browser security models and potentially escalate privileges. When exploited successfully, the vulnerability enables attackers to install malware, modify system files, or establish persistent backdoors on affected systems. The widespread adoption of Internet Explorer 5.x and 6.0 versions at the time of this vulnerability meant that a significant number of users were exposed to this risk, particularly in enterprise environments where older browser versions were commonly deployed. This vulnerability also aligns with ATT&CK technique T1190, which describes exploitation of remote services through buffer overflows, and T1059, which covers execution through scripting languages or command-line interfaces.
Mitigation strategies for this vulnerability involve immediate patching through Microsoft's security updates, which addressed the buffer overflow conditions in the affected ActiveX controls. System administrators should prioritize upgrading to newer versions of Internet Explorer or migrating to more modern browser platforms that have better security controls and more robust memory management. Additionally, implementing browser security restrictions such as disabling ActiveX controls, using enhanced security configurations, and deploying application whitelisting solutions can provide defense-in-depth measures. The vulnerability also underscores the importance of maintaining up-to-date security patches and conducting regular vulnerability assessments, particularly for legacy systems that may continue to operate in enterprise environments. Organizations should consider implementing network segmentation and monitoring solutions to detect potential exploitation attempts and ensure that older browser versions are properly deprecated and removed from production environments.