alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Kimsuky CnC AppKey Request"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/service"; startswith; content:"/appkey"; endswith; fast_pattern; http.header_names; content:!"|0d 0a|user-agent|0d 0a|"; nocase; content:!"|0d 0a|referer|0d 0a|"; nocase; reference:url,aryaka.com/blog/kimsuky-apt-stealth-malware-social-engineering; classtype:command-and-control; sid:2063832; 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_06_24, deployment Perimeter, malware_family Kimsuky, confidence High, signature_severity Critical, tag c2, updated_at 2025_07_31, former_sid 2863014, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:src_ip;)