GEN:SID 1:371
Message ICMP PING Cisco Type.x
Summary This event is generated when an ICMP echo request is made from a Cisco IOS 9.x system.
Impact Information gathering.  An ICMP echo request can determine if a host is active.
Detailed Information An ICMP echo request is used by the ping command to elicit an ICMP echo reply from a listening live host.  An echo request that originates from a system running Cisco IOS 9.x contains a unique payload in the message request.
Affected Systems All
Attack Scenarios An attacker may attempt to determine live hosts in a network prior to launching an attack.
Ease of Attack Simple
Corrective Action Block inbound ICMP echo requests.
Additional References Arachnids:
http://www.whitehats.com/info/IDS153
Rule References arachnids: 153