Rule -- Sid: 995 -- Summary: This event is generated when an attempt is made to request an HTTP-based password change. -- Impact: Information gathering/remote access. Error messages from failed password changes can indicate whether a given account exists on the server. Successful password changes can allow remote access to the server. -- Detailed Information: Microsoft Internet Information Services (IIS) Version 4 servers that were upgraded from IIS 2 or 3 have a legacy ism.dll file that allows web-based administration. Upon sending a request to ism.dll, the user will be prompted for a userid and password. An attacker can attempt to brute force guess a password, allowing remote access to the server. -- Affected Systems: Microsoft IIS 4.0 servers upgraded from IIS 2.0 or 3.0 -- Attack Scenarios: An attacker can request password changes to discover existing accounts or brute force password changes. -- Ease of Attack: Simple. -- False Positives: None Known. -- False Negatives: None Known. -- Corrective Action: Upgrade to a more current version of ISS. Consider running the IIS Lockdown Tool to disable unnecessary functionality. -- Contributors: Original rule writer unknown Modified by Brian Caswell <bmc@sourcefire.com> Sourcefire Research Team Judy Novak <judy.novak@sourcefire.com> -- Additional References: CVE http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-1999-1538 Bugtraq http://www.securityfocus.com/bid/189 --
