CVE-2000-0098 is a medium severity vulnerability affecting Microsoft Index Server version 2.0. The vulnerability allows remote attackers to determine the real physical path of a web directory hosted by the Index Server. This is achieved by sending a specially crafted request to an Internet Data Query (IDQ) file that does not exist on the server. When the server processes this invalid request, it inadvertently discloses the actual file system path of the web directory. This information disclosure vulnerability does not allow attackers to modify data or disrupt service directly but compromises confidentiality by revealing internal server structure details. The vulnerability requires no authentication and can be exploited remotely over the network, making it accessible to any attacker with network access to the affected server. The CVSS base score is 5.0, reflecting a medium severity level, with the vector indicating network attack vector, low attack complexity, no authentication required, and partial confidentiality impact without integrity or availability impact. Microsoft has released patches addressing this vulnerability, as documented in their security bulletin MS00-006.

For European organizations, this vulnerability poses a risk primarily related to information disclosure. Revealing the real path of web directories can aid attackers in crafting more targeted attacks, such as directory traversal, file inclusion, or privilege escalation exploits. Although the vulnerability itself does not allow direct code execution or data modification, the disclosed information can be a valuable reconnaissance asset in a multi-stage attack. Organizations running legacy Microsoft Index Server 2.0, particularly in sectors with sensitive data or critical infrastructure, could see increased risk if attackers leverage this information to escalate privileges or access protected resources. Given the age of the vulnerability and the product, most modern environments are unlikely to be affected; however, legacy systems in use within some European organizations could still be vulnerable. This could be particularly relevant for public sector entities, educational institutions, or smaller enterprises that have not fully migrated to newer web technologies.

The primary mitigation is to apply the official Microsoft patch provided in security bulletin MS00-006, which addresses this information disclosure vulnerability. Organizations should verify that all instances of Microsoft Index Server 2.0 are updated accordingly. Additionally, network-level controls such as firewall rules should restrict access to the Index Server to trusted internal networks or VPN users only, minimizing exposure to external attackers. Web server configurations can be hardened to prevent detailed error messages or path disclosures by disabling verbose error reporting. Legacy systems should be evaluated for upgrade or replacement with modern, supported web server technologies to eliminate the risk of this and other legacy vulnerabilities. Regular vulnerability scanning and penetration testing can help identify any remaining exposures related to this or similar vulnerabilities.