alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Bitshifter Ransomware CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php?root="; fast_pattern; pcre:"/^[a-f0-9]{16}$/Ri"; http.accept; content:"text/plain"; depth:10; endswith; http.protocol; content:"HTTP/1.0"; http.header_names; content:"|0d 0a|Host|0d 0a|"; depth:8; content:!"Referer|0d 0a|"; content:!"Accept-"; reference:md5,d01229914a6b57387e2c963e3aadbc1f; classtype:command-and-control; sid:2024489; rev:5; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_07_21, deployment Perimeter, malware_family Ransomware, malware_family Bitshifter, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_11_05, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)