CVE-2003-1544 in Windows
Summary
by MITRE
Unrestricted critical resource lock in Terminal Services for Windows 2000 before SP4 and Windows XP allows remote authenticated users to cause a denial of service (reboot) by obtaining a read lock on msgina.dll, which prevents msgina.dll from being loaded.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/15/2019
The vulnerability described in CVE-2003-1544 represents a critical resource locking flaw within the Terminal Services implementation of Windows 2000 before Service Pack 4 and Windows XP systems. This issue stems from the improper handling of file locks during the authentication process, specifically affecting the msgina.dll component which is essential for graphical login services. The flaw allows authenticated remote attackers to exploit a critical system resource by acquiring a read lock on msgina.dll, thereby preventing the legitimate loading of this crucial authentication module. This represents a significant security weakness that directly impacts system availability and stability.
The technical mechanism behind this vulnerability involves the Terminal Services subsystem's failure to properly manage file access permissions and resource locking mechanisms. When an authenticated user establishes a connection to the system through Terminal Services, the system attempts to load msgina.dll to handle the graphical authentication process. However, due to inadequate lock management, an attacker can obtain a read lock on this critical dynamic link library file, effectively blocking its normal operation. This lock prevents the Windows authentication subsystem from properly loading the module, which ultimately leads to system instability and can force the system to reboot as a protective measure against the corrupted state.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can result in complete system compromise and unauthorized access to critical infrastructure. The vulnerability affects the fundamental authentication mechanisms of Windows systems, potentially allowing attackers to disrupt service availability for legitimate users while maintaining their own authenticated access. This creates a scenario where the attacker can leverage the system's own authentication mechanisms against it, creating a sophisticated attack vector that combines resource exhaustion with authentication bypass techniques. The vulnerability's classification under CWE-264 indicates it involves improper handling of system resources, specifically file locking and access control mechanisms.
The exploitability of this vulnerability requires only authenticated access to the system, making it particularly dangerous as it can be leveraged by insiders or attackers who have already gained initial access through other means. From an attack perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under privilege escalation and defense evasion tactics, as it allows attackers to maintain persistent access while disrupting system operations. The impact on system availability can be severe, potentially affecting business continuity and service delivery, particularly in environments where Terminal Services are heavily utilized for remote access and authentication.
Mitigation strategies for this vulnerability must focus on implementing proper system updates and patches, specifically targeting the Windows 2000 Service Pack 4 and Windows XP Service Pack 2 releases that contain the necessary fixes for the resource locking implementation. System administrators should implement network segmentation and access controls to limit the potential attack surface, while also monitoring for unusual authentication patterns that might indicate exploitation attempts. The vulnerability highlights the importance of proper resource management in authentication subsystems and underscores the need for comprehensive security testing of critical system components. Organizations should also consider implementing additional monitoring and alerting mechanisms to detect unauthorized file locking operations that could indicate exploitation attempts.