CVE-2001-0500 in Indexing Service
Summary
by MITRE
Buffer overflow in ISAPI extension (idq.dll) in Index Server 2.0 and Indexing Service 2000 in IIS 6.0 beta and earlier allows remote attackers to execute arbitrary commands via a long argument to Internet Data Administration (.ida) and Internet Data Query (.idq) files such as default.ida, as commonly exploited by Code Red.
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Analysis
by VulDB Data Team • 10/06/2025
The vulnerability described in CVE-2001-0500 represents a critical buffer overflow flaw within the ISAPI extension component of Microsoft Index Server 2.0 and Indexing Service 2000. This vulnerability specifically affects Internet Information Services 6.0 beta versions and earlier installations, creating a significant security risk for web server environments. The flaw exists within the idq.dll file which handles Internet Data Query operations, making it a prime target for remote code execution attacks that can compromise entire server infrastructures.
The technical implementation of this vulnerability stems from inadequate input validation within the ISAPI extension's processing of arguments passed to .ida and .idq files. When attackers submit excessively long argument strings to these files, particularly default.ida which serves as the default configuration file, the application fails to properly bounds-check the input data. This lack of proper buffer management causes the program to overwrite adjacent memory locations, potentially allowing attackers to inject and execute malicious code with the privileges of the web server process. The vulnerability maps directly to CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in web server components.
The operational impact of this vulnerability extends far beyond simple denial of service scenarios, as it provides attackers with complete remote code execution capabilities on affected systems. The exploitation technique commonly employed by the Code Red worm demonstrates how attackers can leverage this flaw to gain unauthorized access to web servers, potentially leading to full system compromise, data theft, or use as a launching point for further attacks within network infrastructures. This vulnerability was particularly dangerous because it affected widely deployed server components and could be exploited automatically by malware, making it a prime target for rapid propagation across vulnerable networks.
Organizations affected by this vulnerability should implement immediate mitigations including applying the relevant Microsoft security patches, disabling unnecessary ISAPI extensions, and restricting access to .ida and .idq files through proper access control mechanisms. Network segmentation and intrusion detection systems can help identify exploitation attempts, while regular security audits should verify that vulnerable components have been properly updated or removed from production environments. The ATT&CK framework categorizes this vulnerability under T1210 - Exploitation of Remote Services, highlighting the importance of maintaining up-to-date server software and implementing proper network security controls to prevent unauthorized remote code execution.