alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE TrustConnect RAT CnC Activity (Failed Registration)"; flow:established,to_client; flowbits:isset,ET.TrustConnect.Reg; http.response_body; bsize:54; content:"|7b 22|message|22 3a 22|Invalid|20|or|20|missing|20|registration|20|API|20|key|2e 22 7d|"; threshold:type limit,count 1,seconds 300,track by_src; reference:md5,128e8469959cdb0a8e7e29eb84af0e79; classtype:command-and-control; sid:2067804; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2026_02_17, deployment Perimeter, deployment SSLDecrypt, malware_family TrustConnect, confidence High, signature_severity Critical, tag c2, updated_at 2026_02_23, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:dest_ip;)