CVE-2002-0726 in TSAC ActiveX Control
Summary
by MITRE
Buffer overflow in Microsoft Terminal Services Advanced Client (TSAC) ActiveX control allows remote attackers to execute arbitrary code via a long server name field.
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Analysis
by VulDB Data Team • 05/20/2019
The vulnerability identified as CVE-2002-0726 represents a critical buffer overflow flaw within Microsoft Terminal Services Advanced Client TSAC ActiveX control. This vulnerability specifically targets the handling of server name inputs within the ActiveX component that facilitates remote desktop connections through Terminal Services. The flaw manifests when the control processes a server name field that exceeds the allocated buffer space, creating an exploitable condition that can be leveraged by remote attackers to execute arbitrary code on vulnerable systems. The ActiveX control operates within web browsers and applications that support ActiveX technology, making it accessible through various attack vectors including malicious websites and email attachments that embed the vulnerable component.
The technical implementation of this buffer overflow stems from inadequate input validation within the TSAC ActiveX control's server name processing routine. When a maliciously crafted server name exceeds the predetermined buffer limits, the excess data overflows into adjacent memory regions, potentially corrupting critical program structures or injecting malicious code. This type of vulnerability falls under CWE-121, which categorizes buffer overflow conditions where insufficient boundary checking allows memory to be overwritten. The vulnerability is particularly dangerous because it can be triggered through web-based attacks without requiring any special privileges or user interaction beyond visiting a malicious webpage containing the vulnerable ActiveX control.
The operational impact of CVE-2002-0726 extends beyond simple code execution, as it provides attackers with a pathway to compromise entire systems through the Terminal Services infrastructure. When successfully exploited, the vulnerability allows remote code execution with the privileges of the user running the vulnerable application, potentially enabling full system compromise. This vulnerability is particularly concerning in enterprise environments where Terminal Services is commonly deployed for remote access and administration purposes. The attack surface is broad as the vulnerable ActiveX control can be loaded through Internet Explorer or other applications that support ActiveX, making it accessible through various phishing campaigns and malicious website delivery methods. Security researchers have noted that this vulnerability aligns with ATT&CK technique T1059.007, which covers the execution of commands through scripting languages, as the exploitation can result in arbitrary code execution within the target system context.
Mitigation strategies for CVE-2002-0726 should focus on immediate remediation through Microsoft security updates, as the vendor provided patches to address the buffer overflow condition in the TSAC ActiveX control. Organizations should implement network-based protections including firewall rules that block access to Terminal Services ports when not required, and disable ActiveX controls in web browsers for users who do not require Terminal Services functionality. Additionally, security awareness training should emphasize the dangers of visiting untrusted websites that might contain malicious ActiveX controls. The vulnerability demonstrates the importance of proper input validation and memory management practices, particularly in components that handle user-supplied data. Organizations should also consider implementing application whitelisting policies to prevent execution of untrusted ActiveX controls, and conduct regular security assessments to identify and remediate similar vulnerabilities in legacy components. The incident highlights the need for comprehensive vulnerability management programs that address both current and legacy software components that may contain known security flaws.