alert tcp-pkt $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE PackClient RAT Heartbeat Response From C2"; flow:established,to_client; flowbits:isset,ET.PackClient_RAT.Heartbeat; dsize:8; content:"|04 00 40 5a 02 00 00 00|"; fast_pattern; reference:md5,c55f9bc3c53ac32e6169ad3cc8b2ce49; classtype:trojan-activity; sid:2069887; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, tls_state plaintext, created_at 2026_06_10, deployment Perimeter, malware_family PackClient_RAT, performance_impact Low, confidence High, signature_severity Major, tag RAT, updated_at 2026_06_10; target:dest_ip;)