CVE-1999-1579 in Windows
Summary
by MITRE
The Cenroll ActiveX control (xenroll.dll) for Terminal Server Editions of Windows NT 4.0 and Windows NT Server 4.0 before SP6 allows remote attackers to cause a denial of service (resource consumption) by creating a large number of arbitrary files on the target machine.
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Analysis
by VulDB Data Team • 12/26/2024
The CVE-1999-1579 vulnerability resides within the Cenroll ActiveX control xenroll.dll which is part of Terminal Server Editions of Windows NT 4.0 and Windows NT Server 4.0 before Service Pack 6. This ActiveX control is designed to handle certificate enrollment processes for terminal server environments, making it a critical component for secure remote access operations. The vulnerability manifests as a resource exhaustion flaw that can be exploited through improper input validation and file creation handling within the control's implementation. The issue stems from the control's inability to properly manage file system operations when processing user-supplied data, creating a pathway for malicious actors to consume system resources through excessive file creation.
This vulnerability represents a classic example of insufficient resource management and lacks proper bounds checking in the ActiveX control's file handling routines. The flaw allows remote attackers to trigger a denial of service condition by crafting specific inputs that cause the control to create an arbitrary number of files on the target system. The technical implementation appears to lack proper validation of file paths, names, or creation parameters, enabling attackers to specify multiple file creation operations that exhaust available disk space or file handles. The vulnerability is particularly concerning because it affects server editions of Windows NT 4.0, which were commonly deployed in enterprise environments where system availability is paramount. The exploitation technique involves sending specially crafted data to the ActiveX control that triggers the file creation process without proper resource limits or cleanup mechanisms, leading to system resource exhaustion and potential complete system unavailability.
The operational impact of CVE-1999-1579 extends beyond simple denial of service conditions to potentially compromise entire terminal server environments. When exploited successfully, the vulnerability can cause system instability, application crashes, and complete service disruption for legitimate users attempting to access terminal server resources. The resource consumption aspect means that attackers can effectively render the system unusable by filling up disk space or exhausting file system handles, creating a persistent availability issue that requires manual intervention to resolve. This vulnerability particularly affects organizations relying on Windows NT 4.0 terminal servers for remote access, as it provides a straightforward method for disrupting business operations without requiring advanced exploitation techniques or elevated privileges. The impact is amplified in environments where terminal servers handle critical business processes, as the disruption can cascade to affect multiple users and applications dependent on the affected system.
Organizations should implement immediate mitigations including disabling the vulnerable ActiveX control through group policy settings or registry modifications, applying the available Service Pack 6 update for Windows NT 4.0, and implementing network segmentation to limit exposure to untrusted users. The vulnerability aligns with CWE-400 which catalogs "Uncontrolled Resource Consumption" as a common weakness in software design, specifically addressing the lack of proper resource management in system components. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for "Endpoint Denial of Service" and represents a classic example of how legacy software components can create persistent security risks. System administrators should also consider implementing monitoring solutions to detect unusual file creation patterns that might indicate exploitation attempts, and establish incident response procedures for handling resource exhaustion events. The vulnerability serves as a reminder of the importance of proper input validation, resource management, and regular patching in maintaining secure system environments, particularly for legacy systems that may not receive ongoing security updates.