Rule:--Sid:2189--Summary:This event is generated when a suspicious packet using an unusual protocol is sent to a router.--Impact:Denial of Service (DoS).--Detailed Information:A vulnerability exists in multiple Cisco IOS versions such that a Denialof Service condition can be issued against a device by sending multiple packets using IP protocols 53, 55, 77 and 103 directly to that device.Cisco IOS processes these packets and under certain circumstances, can be made to incorrectly flag an input interface as being full.--Affected Systems:Multiple versions of Cisco IOS.--Attack Scenarios:An attacker may send a large number of IP packets using one of the protocols 53, 55, 77 or 103 directly to a router. Exploit code exists.--Ease of Attack:Simple. Expoit code exists.--False Positives:None known.--False Negatives:None known.--Corrective Action:Upgrade to the latest non-affected version of the software.Apply the appropriate vendor supplied patches.--Contributors:Sourcefire Research TeamBrian Caswell <bmc@sourcefire.com>Nigel Houghton <nigel.houghton@sourcefire.com>--Additional References:--