alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MSIL/Hidden-Tear Variant Ransomware CnC Checkin"; flow:established,to_server; http.uri; content:".php?rid=ClsgIFVzZXItSUQgIF0gID"; fast_pattern; pcre:"/\.php\?rid=(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/i"; http.header; header_lowercase; content:"ransom|3a 20|Client|0d 0a|"; http.header_names; to_lowercase; content:!"|0d 0a|user-agent|0d 0a|"; content:!"|0d 0a|referer|0d 0a|"; reference:md5,b991a99335b01bed8da4401fee1f2d45; classtype:command-and-control; sid:2024204; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_04_12, deployment Perimeter, malware_family Ransomware, malware_family Hidden_Tear, confidence High, signature_severity Major, tag Ransomware, updated_at 2024_04_20, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)