NF – ISAKMP VPN Connection setup from host to outbound destination – Windows 2000
The rule detects ISAKMP VPN connection setups originating from the internal network to an outbound destination (EXTERNAL_NET), with a specific ISAKMP Initiator cookie value (00 00 00 02). The rule is intended to provide visibility into ISAKMP VPN connection attempts, particularly those related to Windows 2000 hosts, and assist in monitoring and securing VPN communication in the network.
Signature
alert udp $HOME_NET 500 -> $EXTERNAL_NET 500 (msg:"NF - ISAKMP VPN Connection setup from host to outbound destination - Windows 2000"; content:"|00 00 00 02|"; reference:url,networkforensic.dk; metadata:29112018; classtype:policy-violation; sid:5027201; rev:1;)
Recommendations/Investigative actions
Authorize the connection. If the connection was approved as a network engineer accessing the PLC - archive and baseline the rule. If not - check the connection and investigate the relevant IP address.
Relations to other alerts