CVE-2000-0302 is a vulnerability in Microsoft Index Server version 2.0 that allows remote attackers to view the source code of ASP (Active Server Pages) files. The issue arises because the server improperly handles requests to the null.htw URL when the CiWebHitsFile argument includes a filename appended with a '%20' (URL-encoded space). This causes the server to bypass normal processing and reveal the raw source code of the ASP files instead of executing them. Since ASP files often contain server-side scripts, including database queries, business logic, and potentially sensitive information such as credentials or configuration details, exposing their source code can lead to significant information disclosure. The vulnerability is remotely exploitable over the network without requiring authentication or user interaction, making it accessible to any attacker who can reach the affected server. The CVSS v2 base score is 5.0 (medium severity), reflecting partial confidentiality impact with no impact on integrity or availability. A patch addressing this vulnerability was released by Microsoft as part of the MS00-006 security bulletin. No known exploits have been reported in the wild, but the vulnerability remains a risk if unpatched.

For European organizations, this vulnerability poses a risk of sensitive information leakage from web servers running Microsoft Index Server 2.0 with ASP applications. Disclosure of ASP source code can reveal application logic, database connection strings, credentials, or other sensitive data, which attackers can leverage to mount further attacks such as SQL injection, privilege escalation, or lateral movement. Although the vulnerability does not directly allow code execution or denial of service, the information disclosure can significantly aid attackers in compromising systems. Organizations in sectors with high web application usage, such as finance, government, healthcare, and e-commerce, are particularly at risk. Since the vulnerability is remotely exploitable without authentication, any exposed Index Server instances accessible from the internet or internal networks could be targeted. Given the age of the vulnerability (published in 2000), it is less likely to affect modern environments but may still be present in legacy systems or poorly maintained infrastructure within European organizations.

European organizations should immediately verify whether any Microsoft Index Server 2.0 instances are in use, especially those hosting ASP applications. If found, they must apply the official patch provided in Microsoft's MS00-006 security bulletin to remediate the vulnerability. If patching is not feasible due to legacy constraints, organizations should consider isolating affected servers from public networks, restricting access via firewalls or network segmentation, and disabling the Index Server service if not required. Additionally, web application firewalls (WAFs) can be configured to block requests containing suspicious URL patterns such as appended '%20' characters targeting null.htw URLs. Regular security audits and vulnerability scans should be conducted to detect any unpatched instances. Finally, organizations should plan to upgrade legacy web infrastructure to supported and secure platforms to avoid exposure to such outdated vulnerabilities.