alert tcp-pkt $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32.Application.ThunderN.A Checkin"; flow:established,to_server; stream_size:server,<,5; content:"|1b 00 0c|"; startswith; content:"Startup102_embedding|ea 03 01 00 00 00|"; endswith; fast_pattern; reference:md5,1f1ef30f55a9b69bf0b8706e479beca0; classtype:command-and-control; sid:2034275; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_10_28, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_10_28;)