alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE GCleaner Loader CnC Checkin (/ycl)"; flow:established,to_server; urilen:4; http.method; content:"GET"; http.uri; content:"/ycl"; fast_pattern; http.user_agent; bsize:1; pcre:"/^.$/"; reference:md5,e627cad277450feb0685a9b2abd981f8; reference:md5,9c44f98f428e7a562553944c3067f73b; classtype:trojan-activity; sid:2064262; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state plaintext, created_at 2025_09_02, deployment Perimeter, confidence High, signature_severity Critical, tag c2, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_09_02, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:src_ip;)