alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Mermaid Ransomware Variant CnC Activity M4"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"=ID|3a 20|"; content:"|20 20|Key1|3a 20 20|"; content:"|20 20|Key2|3a 20 20|"; fast_pattern; http.user_agent; bsize:38; content:"Mozilla/3.0 (compatible|3b 20|Indy Library)"; http.header_names; content:!"Referer"; reference:md5,fc78e6e58352151fb77a4b92f239d381; classtype:command-and-control; sid:2029496; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_02_19, deployment Perimeter, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_02_19, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)