alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MSIL/Karmen Ransomware CnC Activity"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"data.php?id="; fast_pattern; pcre:"/\.php\?id=[A-Za-z0-9]{10,20}(?:&key=[A-Za-z0-9]{10,30})?$/i"; http.header; pcre:"/^Host\x3a\x20[^\r\n]+\r\n(?:Connection\x3a\x20Keep-Alive\r\n)?(?:\r\n)?$/mi"; http.header_names; content:!"User-Agent|0d 0a|"; content:!"Accept"; content:!"Referer|0d 0a|"; reference:md5,05427ed1c477cc01910eb9adbf35068d; classtype:command-and-control; sid:2024239; rev:5; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_03_15, deployment Perimeter, malware_family Karmen_Ransomware, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_25, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)