SharePoint exposed web services
Description
Microsoft SharePoint exposes several administrative web services by default. When SharePoint is misconfigured, these web services may be accessible to unauthenticated users without proper access controls. This allows anonymous users to interact with internal SharePoint APIs that should be restricted to authenticated administrators or authorized service accounts.
Remediation
Restrict access to SharePoint web services to authenticated users only. Configure web.config files for each exposed web service directory (typically located in _vti_bin) to require authentication. Add or modify the following configuration within the section:
<authorization> <deny users="?" /> <allow users="*" /> </authorization>
Alternatively, use SharePoint Central Administration to configure web application policies that enforce authentication requirements. Verify the configuration by attempting to access web services (such as /_vti_bin/lists.asmx) while logged out - access should be denied. Regularly audit SharePoint permissions and review IIS authentication settings to ensure anonymous access is disabled for administrative endpoints.