CVE-2000-0097 in Index Server
Summary
by MITRE
The WebHits ISAPI filter in Microsoft Index Server allows remote attackers to read arbitrary files, aka the "Malformed Hit-Highlighting Argument" vulnerability.
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Analysis
by VulDB Data Team • 10/19/2025
The CVE-2000-0097 vulnerability represents a critical security flaw in Microsoft Index Server's WebHits ISAPI filter that enables remote attackers to access arbitrary files on the affected system. This vulnerability specifically exploits a weakness in how the filter processes hit-highlighting arguments, creating a path for unauthorized file access that can potentially expose sensitive system information. The issue arises from inadequate input validation within the ISAPI filter component, which fails to properly sanitize user-supplied parameters before processing them in file access operations.
The technical implementation of this vulnerability stems from a buffer overflow condition and improper parameter handling within the WebHits ISAPI filter module. When the filter receives malformed hit-highlighting arguments, it fails to validate the input properly, allowing attackers to craft malicious requests that can traverse directory structures and access files outside the intended scope. This flaw operates at the application layer and leverages the ISAPI filter architecture to bypass normal access controls, making it particularly dangerous as it can be exploited without authentication. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-20, which covers improper input validation, both of which are fundamental weaknesses in software security design.
From an operational perspective, this vulnerability creates significant risk for organizations running Microsoft Index Server environments, as it can lead to complete system compromise through information disclosure. Attackers can leverage this flaw to access configuration files, database files, and other sensitive resources that may contain credentials, system information, or proprietary data. The impact extends beyond simple file reading, as the ability to traverse file systems can enable attackers to gather intelligence for further exploitation or to establish persistence within the compromised environment. This vulnerability is particularly concerning because it can be exploited remotely, meaning attackers do not need physical access or local privileges to exploit the flaw, making it a prime target for automated attacks.
The exploitation of CVE-2000-0097 aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to credential access and reconnaissance activities. The vulnerability can be categorized under ATT&CK technique T1003 for OS credential dumping and T1083 for file and directory discovery, as attackers can use this flaw to explore system directories and extract valuable information. Organizations should consider implementing network segmentation and access controls to limit exposure, while also ensuring that vulnerable systems are patched or isolated from untrusted networks. The vulnerability demonstrates the importance of proper input validation and the potential consequences of inadequate security measures in web server components, particularly those that process user-supplied data through ISAPI filters. Security professionals should prioritize patch management for legacy systems and implement monitoring to detect anomalous file access patterns that may indicate exploitation attempts.
Microsoft addressed this vulnerability through security updates that corrected the input validation mechanisms within the WebHits ISAPI filter, requiring proper sanitization of hit-highlighting arguments before file access operations. Organizations should verify that all affected systems have received the appropriate patches and consider implementing additional security controls such as web application firewalls and intrusion detection systems to provide defense in depth against similar vulnerabilities. The incident highlights the critical importance of secure coding practices and the need for comprehensive security testing of web server components that handle user input, particularly those operating within ISAPI filter architectures where security failures can have widespread system impact.