alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE S400 RAT Server Response"; flow:established,to_client; stream_size:client,<,10; content:"|7c|S400|7c|"; within:16; content:"|7c|S400|7c|"; distance:32; within:6; content:"|7c|S400|7c|"; distance:0; reference:md5,41ca8d5782ef5ac7a371b44f51dc48d9; classtype:command-and-control; sid:2034064; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_09_30, deployment Perimeter, malware_family S400, confidence High, signature_severity Major, tag RAT, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_09_30;)