Rule History

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE CastleBot CnC Exfil (POST)"; flow:established,to_server; urilen:14; http.method; content:"POST"; http.uri; content:"/service/tasks"; fast_pattern; http.user_agent; bsize:<26; pcre:"/^(?:[a-zA-Z0-9]{20,25})$/"; http.request_body; content:"Content|2d|Disposition|3a 20|form|2d|data|3b 20|name|3d 22|data|22|"; reference:md5,1a3896a986195c277f1547706dbdea08; reference:md5,f75bb2393f80bf30c4788c82f3a7dadf; reference:url,ibm.com/think/x-force/dissecting-castlebot-maas-operation; classtype:command-and-control; sid:2064208; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_08_28, deployment Perimeter, deployment SSLDecrypt, malware_family CastleBot, confidence High, signature_severity Critical, tag c2, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_08_28, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:src_ip;)