alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Felismus CnC Beacon 1"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php?V="; fast_pattern; content:"&U="; distance:0; http.header; content:"Windows NT"; content:"Referer|3a|"; content:".php|0d 0a|"; distance:0; http.header_names; content:!"Accept-"; reference:url,blogs.forcepoint.com/security-labs/playing-cat-mouse-introducing-felismus-malware; reference:md5,8de3f20d94611e0200c484e42093f447; classtype:command-and-control; sid:2024176; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_04_04, deployment Perimeter, malware_family Felismus, confidence High, signature_severity Major, tag Felismus, tag c2, updated_at 2020_09_14, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)