alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Buran Ransomware Activity M1"; flow:established,to_server; http.method; content:"GET"; http.user_agent; content:"BURAN"; fast_pattern; bsize:5; http.referer; content:!"."; pcre:"/^[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$/i"; http.header_names; content:!"Connection"; content:!"Cache"; content:!"Accept"; classtype:trojan-activity; sid:2027446; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_06_10, deployment Perimeter, malware_family Buran, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_31, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)