alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Shifr Ransomware Malicious Domain in SNI Observed"; flow:established,to_server; tls.sni; content:"v5t5z6a55ksmt3oh.onion"; startswith; fast_pattern; reference:md5,7a8c9fbfad9a817c0a10fed926f134c2; classtype:trojan-activity; sid:2024486; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_07_20, deployment Perimeter, malware_family Shifr, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_13, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)