alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Atemu RAT CnC Checkin Attempt"; flow:established,to_server; http.method; content:"POST"; http.uri; bsize:9; content:"/api/auth"; http.header; content:"X-API-KEY|3a 20|"; pcre:"/^[a-f0-9]{64}/R"; http.content_type; bsize:16; content:"application|2f|json"; http.request_body; content:"|7b 22|machine_id|22 3a 22|"; startswith; fast_pattern; pcre:"/^[a-f0-9]{32}\x22/R"; content:"|22|version|22 3a 22|"; reference:md5,a3ce0c6600781e0196aad961e92123ed; classtype:trojan-activity; sid:2068885; 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 TLSDecrypt, created_at 2026_04_21, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, signature_severity Major, tag Atemu_RAT, updated_at 2026_04_21, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1573, mitre_technique_name Encrypted_Channel; target:src_ip;)