CVE-2011-0901 in Terminal Server Client
Summary
by MITRE
Multiple stack-based buffer overflows in the tsc_launch_remote function (src/support.c) in Terminal Server Client (tsclient) 0.150, and possibly other versions, allow user-assisted remote attackers to execute arbitrary code via a .RDP file with a long (1) username, (2) password, or (3) domain argument. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 03/04/2025
The vulnerability identified as CVE-2011-0901 represents a critical stack-based buffer overflow flaw within the Terminal Server Client tsclient component version 0.150 and potentially other iterations. This security weakness exists within the tsc_launch_remote function located in the src/support.c source file, creating a significant attack surface that could be exploited by malicious actors. The flaw specifically manifests when processing .RDP files, which are used to establish remote desktop connections, making it particularly dangerous in environments where remote access is commonly utilized. The vulnerability's classification as a user-assisted remote attack means that successful exploitation requires some form of user interaction, typically through the deliberate manipulation of RDP connection files by an attacker. This characteristic reduces the attack surface compared to fully autonomous exploits but still presents a substantial risk given the prevalence of RDP-based remote access solutions in enterprise environments.
The technical implementation of this vulnerability stems from inadequate input validation within the tsclient application's handling of RDP file parameters. When the application processes .RDP files containing excessively long username, password, or domain arguments, the tsc_launch_remote function fails to properly bounds-check these inputs before copying them into fixed-size stack buffers. This fundamental flaw allows attackers to overwrite adjacent memory locations, potentially corrupting the stack and enabling arbitrary code execution. The buffer overflow occurs because the application does not enforce maximum length constraints on these parameters, allowing maliciously crafted inputs to exceed allocated buffer boundaries. The stack-based nature of the vulnerability means that the overflow affects the program's execution stack, potentially leading to control flow hijacking through return address corruption or stack pointer manipulation. This type of vulnerability is categorized under CWE-121 as Stack-based Buffer Overflow, which is a well-documented weakness in software development practices involving improper buffer management and insufficient input validation.
The operational impact of this vulnerability extends beyond simple code execution, as it could enable attackers to gain unauthorized access to systems running vulnerable versions of the Terminal Server Client. The attack vector's user-assisted nature suggests that successful exploitation would require social engineering or other means to convince a user to open a maliciously crafted RDP file. However, the potential for privilege escalation and system compromise remains significant, particularly in enterprise environments where remote desktop protocols are extensively used. Attackers could leverage this vulnerability to establish persistent access, escalate privileges, or deploy additional malware within the target network. The vulnerability's presence in tsclient software indicates that it affects Windows systems using Remote Desktop Protocol connections, which are common in corporate and institutional settings. The implications for network security are severe, as this could allow attackers to bypass traditional network security controls and directly compromise endpoints, potentially leading to data breaches, lateral movement, or complete system takeover. Organizations utilizing remote desktop solutions would be particularly vulnerable, as the attack requires minimal technical sophistication beyond the ability to distribute malicious RDP files.
Mitigation strategies for CVE-2011-0901 should prioritize immediate software updates and patches from the vendor, as the vulnerability affects specific versions of the tsclient component. System administrators should implement network monitoring to detect suspicious RDP file access patterns and unauthorized file distribution attempts. The principle of least privilege should be enforced to limit the impact of successful exploitation, ensuring that users have minimal necessary permissions for remote access operations. Network segmentation and firewall rules can help restrict access to RDP services, reducing the attack surface for this vulnerability. Additionally, endpoint protection solutions should be configured to scan and block suspicious RDP files, particularly those with unusual parameters or from untrusted sources. Security awareness training for users should emphasize the dangers of opening unknown or unexpected RDP files, as the user-assisted nature of the attack relies on human interaction. The vulnerability's characteristics align with ATT&CK technique T1071.004 for Application Layer Protocol: Remote Desktop Protocol, which focuses on the exploitation of RDP services for initial access and lateral movement. Organizations should also consider implementing automated patch management systems to ensure all instances of the vulnerable software are promptly updated, as the vulnerability affects potentially multiple versions of the tsclient component, making comprehensive patching essential for effective defense against this specific threat.