CVE-2000-0858 in IIS
Summary
by MITRE
Vulnerability in Microsoft Windows NT 4.0 allows remote attackers to cause a denial of service in IIS by sending it a series of malformed requests which cause INETINFO.EXE to fail, aka the "Invalid URL" vulnerability.
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Analysis
by VulDB Data Team • 05/09/2019
The CVE-2000-0858 vulnerability represents a critical denial of service weakness in Microsoft Windows NT 4.0 systems running Internet Information Services. This flaw specifically targets the INETINFO.EXE process which serves as the core component responsible for managing IIS web server operations. The vulnerability operates through a sophisticated mechanism where malicious actors can craft and transmit specially formatted HTTP requests that exploit inherent weaknesses in the URL parsing and processing routines within the IIS architecture. The attack vector is particularly dangerous because it can be executed remotely without requiring any authentication or prior access to the system, making it an attractive target for cybercriminals seeking to disrupt web services.
The technical implementation of this vulnerability stems from inadequate input validation within the IIS web server software. When INETINFO.EXE processes malformed URL requests, the parsing logic fails to properly handle certain edge cases in URL formatting, leading to memory corruption or stack overflow conditions that ultimately cause the process to crash and terminate. This behavior aligns with CWE-129, which addresses issues related to insufficient input validation, and specifically demonstrates how malformed input can lead to process termination and system instability. The vulnerability operates at the application layer of the network stack, making it particularly challenging to detect and prevent through traditional network security measures. Attackers can leverage this weakness by constructing HTTP requests with malformed URL parameters, encoded characters, or unusual path structures that trigger the specific parsing routines where the flaw exists.
The operational impact of CVE-2000-0858 extends far beyond simple service disruption, as it can effectively render web servers completely inaccessible to legitimate users and potentially impact business operations. When the INETINFO.EXE process fails, all active web connections are terminated and the server becomes unresponsive to incoming requests until the service is manually restarted or the system is rebooted. This vulnerability can be exploited in various attack scenarios including distributed denial of service campaigns where multiple attackers simultaneously target the same vulnerable server, or as part of broader attack strategies where initial access is gained through other means before using this weakness to maintain persistent access or escalate privileges. The vulnerability's classification under the ATT&CK framework would align with the T1499.004 technique for network denial of service, demonstrating how attackers can leverage application-level weaknesses to achieve system-level disruption. Organizations running vulnerable Windows NT 4.0 systems face significant risk of service interruption that can result in financial losses, reputation damage, and compliance violations.
Mitigation strategies for CVE-2000-0858 require immediate attention and comprehensive system hardening approaches. Microsoft released patches and updates specifically addressing this vulnerability through their regular security bulletin process, and organizations should prioritize applying these patches to all affected systems. Network-level protections can include implementing intrusion detection systems that monitor for suspicious URL patterns and configuring firewalls to limit access to web server ports. Additionally, administrators should implement proper input validation at the application level and consider deploying web application firewalls that can identify and block malformed requests before they reach the vulnerable IIS components. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates how legacy systems like Windows NT 4.0 can contain critical weaknesses that remain exploitable for years after their initial discovery. Organizations should also consider implementing redundant web server configurations and load balancing solutions to minimize the impact of single points of failure. Regular security assessments and vulnerability scanning should be conducted to identify other potential weaknesses in the web server infrastructure that could be exploited in similar ways.