CVE-2004-2527 in Windows
Summary
by MITRE
The local and remote desktop login screens in Microsoft Windows XP before SP2 and 2003 allow remote attackers to cause a denial of service (CPU and memory consumption) by repeatedly using the WinKey+"U" key combination, which causes multiple copies of Windows Utility Manager to be loaded more quickly than they can be closed when the copies detect that another instance is running.
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Analysis
by VulDB Data Team • 07/19/2017
This vulnerability exists in Microsoft Windows XP prior to Service Pack 2 and Windows Server 2003 systems where the desktop login screens contain a design flaw that allows remote attackers to perform a denial of service attack through keyboard input manipulation. The issue specifically involves the Windows Utility Manager application which is triggered by the WinKey+"U" key combination, a standard accessibility feature designed to launch utility programs. When an attacker repeatedly presses this key combination, the system attempts to launch multiple instances of the Windows Utility Manager application, creating a cascading effect that rapidly consumes system resources.
The technical flaw stems from inadequate input validation and process management within the Windows login interface. When the WinKey+"U" combination is detected, the system launches the Windows Utility Manager without proper checks to prevent multiple concurrent instances from being created. The application's design includes a mechanism that detects when another instance is running and attempts to close it, but this process creates a race condition where multiple instances are launched faster than they can be properly terminated. This results in a rapid consumption of both cpu cycles and memory resources as each new instance attempts to initialize and then detect the existing process, leading to a resource exhaustion scenario.
The operational impact of this vulnerability is significant as it allows attackers to cause a complete denial of service on affected systems without requiring any special privileges or authentication. The attack can be performed remotely through network-based keyboard input simulation or locally through physical access to the system. The resource consumption pattern causes the system to become unresponsive, making legitimate user login impossible while the system struggles to manage the rapidly spawning processes. This vulnerability effectively renders the system unusable until the attacker stops the attack or the system is manually rebooted, creating a substantial availability risk for targeted systems.
The vulnerability maps to CWE-400, which describes "Uncontrolled Resource Consumption" and aligns with ATT&CK technique T1499.004 for "Toggle System Execution Flag" and T1566.001 for "Phishing via Social Engineering". Organizations should implement immediate mitigations including applying Microsoft Security Update MS05-001 which addresses this specific vulnerability by modifying the Windows login interface to properly handle multiple instances of utility applications. System administrators should also consider disabling unnecessary accessibility features through group policy settings and implementing proper network segmentation to limit remote access to login screens. Additionally, monitoring for unusual keyboard input patterns and implementing resource usage alerts can help detect exploitation attempts before they cause complete system unavailability.