alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET RETIRED Win32/Fabookie.ek CnC Activity M2"; flow:established,to_server; http.start; content:"POST /check/?sid="; startswith; fast_pattern; pcre:"/^\d+&key=[a-f0-9]{32}\sHTTP\/1\./R"; http.header_names; content:!"|0d 0a|Referer|0d 0a|"; http.request_body; pcre:"/^[a-zA-Z0-9+\/]+(?:[a-zA-Z0-9+\/]{2}==|[a-zA-Z0-9+\/]{3}=|[a-zA-Z0-9+\/]{4})$/"; reference:md5,3a8f10a03d9b318bf2826e63279f0422; classtype:command-and-control; sid:2045058; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2023_04_19, deployment Perimeter, former_category MALWARE, malware_family Fabookie, performance_impact Low, confidence High, signature_severity Major, tag Fabookie, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_09_30, reviewed_at 2024_09_30; target:src_ip;)