CVE-2001-1571 in Windows
Summary
by MITRE
The Remote Desktop client in Windows XP sends the most recent user account name in cleartext, which could allow remote attackers to obtain terminal server user account names via sniffing.
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Analysis
by VulDB Data Team • 09/24/2025
The vulnerability described in CVE-2001-1571 represents a critical security flaw in the Windows XP Remote Desktop Protocol implementation that exposes user authentication credentials through network traffic interception. This issue affects the Remote Desktop client component of Microsoft Windows XP operating systems, where the client transmits the most recently used account name in plain text format during connection establishment. The flaw specifically impacts the authentication phase of remote desktop sessions, creating an avenue for malicious actors to capture sensitive information through network sniffing activities.
The technical implementation of this vulnerability stems from the Remote Desktop client's design decision to store and transmit the last used username without encryption or obfuscation. When a user connects to a terminal server using Remote Desktop, the client automatically includes the previously entered username in the initial connection packet, making it visible to anyone who can monitor network traffic. This cleartext transmission occurs before the actual authentication process begins, providing attackers with immediate access to valid account identifiers that can be used for subsequent attacks. The vulnerability is classified under CWE-312, which specifically addresses the exposure of sensitive information through cleartext transmission, and represents a fundamental weakness in the protocol's security architecture.
The operational impact of this vulnerability extends beyond simple credential exposure, as it provides attackers with valuable reconnaissance information that can be leveraged for more sophisticated attacks. An attacker who successfully intercepts this cleartext username can use it as a starting point for password spraying attacks, brute force attempts, or social engineering campaigns. The vulnerability is particularly dangerous in environments where network traffic is not properly secured or encrypted, as it can be exploited through passive network monitoring techniques that require minimal technical expertise. According to ATT&CK framework, this vulnerability maps to T1566, which covers credential harvesting through network sniffing, and T1110, which encompasses credential brute force attacks that can be facilitated by the exposed account information.
Mitigation strategies for CVE-2001-1571 require both immediate and long-term security measures to address the underlying exposure. Organizations should implement network segmentation and encryption protocols to prevent unauthorized traffic interception, ensuring that all Remote Desktop traffic is properly secured through TLS encryption or other secure communication channels. The most effective immediate solution involves updating to patched versions of Windows XP or implementing network monitoring tools that can detect and alert on cleartext credential transmission. Security administrators should also enforce strong password policies and account lockout mechanisms to minimize the impact of credential exposure, while considering the deployment of multi-factor authentication systems that provide additional protection layers beyond simple username-password combinations. Additionally, network administrators should implement proper firewall rules and access controls to restrict Remote Desktop access to trusted networks only, reducing the attack surface available to potential adversaries who might exploit this vulnerability.