CVE-1999-0227 in Windows
Summary
by MITRE
access violation in lsass.exe (lsa/lsarpc) program in windows nt allows a denial of service.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-0227 represents a critical access violation flaw within the Windows NT operating system's security subsystem, specifically affecting the Local Security Authority Subsystem Service (LSASS) process. This vulnerability resides in the lsa/lsarpc component of the Windows NT architecture, which handles remote procedure calls for security-related operations and authentication services. The LSASS.exe process serves as the core component responsible for managing local security policies, validating user credentials, and maintaining security contexts within the Windows NT environment. When exploited, this access violation causes the lsass.exe process to crash or become unresponsive, resulting in a denial of service condition that fundamentally compromises system security and availability.
The technical nature of this vulnerability stems from improper input validation and memory management within the LSA RPC interface implementation. Attackers can craft malicious RPC requests that trigger buffer overflows or invalid memory access patterns when the lsass.exe process attempts to process these malformed inputs. The flaw typically manifests when the system receives specially crafted RPC messages through the lsarpc interface, which lacks adequate bounds checking or sanitization of incoming parameters. This weakness creates a scenario where legitimate security operations can be disrupted through carefully constructed malicious payloads that exploit the underlying memory corruption mechanisms in the Windows NT security subsystem.
The operational impact of CVE-1999-0227 extends beyond simple service disruption to encompass broader security implications within Windows NT environments. When the lsass.exe process becomes unavailable due to this access violation, the entire authentication and authorization framework of the affected system collapses, preventing legitimate users from logging in or accessing system resources. This vulnerability directly affects the availability of critical security services, potentially leaving systems vulnerable to additional attacks while rendering the security infrastructure ineffective. Network administrators face the challenge of maintaining system uptime and user access while dealing with a service that can be easily destabilized through remote exploitation, particularly in domain environments where LSASS plays a central role in maintaining network security posture.
Mitigation strategies for this vulnerability must address both immediate defensive measures and longer-term architectural improvements to prevent exploitation. System administrators should implement network segmentation and access controls to limit exposure to potential attackers who might attempt to exploit this vulnerability through RPC interfaces. The Windows NT security model requires careful configuration of RPC services and the implementation of proper firewall rules to restrict access to the lsarpc endpoints. Organizations should also consider applying security patches and updates from Microsoft as soon as they become available, though in the context of Windows NT this may be limited due to the age of the platform. Additionally, monitoring systems should be configured to detect unusual patterns in LSASS process behavior or RPC traffic that might indicate exploitation attempts, aligning with security best practices for protecting critical system components against denial of service attacks.
This vulnerability demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read conditions in software implementations, and relates to ATT&CK technique T1499.004 for endpoint denial of service attacks. The flaw represents a classic example of how security subsystems can become attack vectors when proper input validation and memory management practices are not implemented. The impact extends beyond immediate service disruption to encompass potential compromise of the entire Windows NT security infrastructure, making this vulnerability particularly dangerous in enterprise environments where authentication and authorization services are critical to system operations.