Rule: -- Sid: 2033 -- Summary: A request has been made to rpc.ypserv from an external source that should not have access to this service. This may be indicative of an intelligence gathering activity as a prelude to a more serious compromise of system resources. service against the target host. -- Impact: Disclosure of sensitive system information to an unauthorized user. Possible denial of service. -- Detailed Information: The rpc.ypserv daemon queries information in the local NIS maps. A response to this query may divulge important information to the user performing the query. This could lead to futher exploitation of resources on the network. In addition, a vulnerability exists in ypserv on some Linux platforms that could lead to a buffer overflow and root compromise of the target host. This is achieved by making a multitude of requests for a NIS map that does not exist. -- Affected Systems: Multiple systems running versions of ypserv prior to 2.5. -- Attack Scenarios: The attacker can craft a malicious request to rpc.ypserv such that valuable information can be returned to the attacker. In the case of a buffer overflow, the attacker might issue a large therefore, be seen many times. -- Ease of Attack: Simple -- False Positives: None Known -- False Negatives: None Known -- Corrective Action: Disallow all RPC requests from external sources and use a firewall to block access to RPC ports from outside the LAN. Upgrade ypserv to the latest version. Use /var/yp/securenets to list the hosts allowed to access this resource where appropriate. -- Contributors: Sourcefire Research Team Brian Caswell <bmc@sourcefire.com> Nigel Houghton <nigel.houghton@sourcefire.com> -- Additional References: Bugtraq: http://www.securityfocus.com/bid/6016 http://www.securityfocus.com/bid/5914 CVE: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-1232 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-1043 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2000-1042 --
