CVE-2011-0900 in Terminal Server Client
Summary
by MITRE
Stack-based buffer overflow in the tsc_launch_remote function (src/support.c) in Terminal Server Client (tsclient) 0.150, and possibly other versions, allows user-assisted remote attackers to execute arbitrary code via a .RDP file with a long hostname argument.
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Analysis
by VulDB Data Team • 03/04/2025
The vulnerability identified as CVE-2011-0900 represents a critical stack-based buffer overflow flaw within the Terminal Server Client tsclient version 0.150 and potentially other iterations. This security weakness resides in the tsc_launch_remote function located in the src/support.c source file, making it a prime target for exploitation by malicious actors who can manipulate the hostname argument within RDP files. The vulnerability operates through a user-assisted remote attack vector, meaning that an attacker must convince a victim to open a specially crafted .RDP file to trigger the exploit, which significantly broadens its potential impact across various network environments.
The technical implementation of this buffer overflow stems from inadequate input validation within the tsc_launch_remote function where the hostname parameter from .RDP files is processed without proper bounds checking. When an attacker crafts a .RDP file containing an excessively long hostname argument, the function fails to properly validate the input length before copying it onto the stack, resulting in a classic stack-based buffer overflow condition. This flaw allows attackers to overwrite adjacent memory locations including return addresses and control data, potentially enabling arbitrary code execution with the privileges of the affected application. The vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is categorized under the broader weakness of buffer overflow conditions that can lead to complete system compromise.
From an operational perspective, this vulnerability presents significant risk to organizations relying on Terminal Server Client implementations for remote desktop connections. The user-assisted nature of the attack means that successful exploitation requires social engineering to convince victims to open malicious RDP files, but once triggered, the consequences can be devastating. Attackers can leverage this vulnerability to execute malicious code on target systems, potentially gaining unauthorized access to sensitive data, establishing persistent backdoors, or using the compromised system as a launch point for further network infiltration. The attack vector specifically targets the RDP file parsing functionality, making it particularly dangerous in environments where users frequently receive and open remote desktop connection files from external sources.
The mitigation strategies for CVE-2011-0900 should prioritize immediate patching of affected tsclient versions to address the buffer overflow condition in the tsc_launch_remote function. Organizations must implement strict input validation controls for all RDP file processing, including length restrictions on hostname parameters and comprehensive sanitization of user-supplied data. Network administrators should consider implementing security controls that prevent the automatic execution of .RDP files from untrusted sources and establish monitoring procedures to detect potential exploitation attempts. Additionally, organizations should conduct regular security assessments of their remote desktop infrastructure and maintain up-to-date threat intelligence to identify potential variants or similar vulnerabilities in related software components. The vulnerability's classification under ATT&CK technique T1210 (Exploitation of Remote Services) highlights the importance of maintaining secure remote access configurations and implementing network segmentation to limit the potential impact of successful exploitation attempts.