alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE FF-RAT Stage 1 CnC Checkin"; flow:to_server,established; http.method; content:"POST"; http.uri; content:".php?hdr_ctx="; fast_pattern; pcre:"/\.php\?hdr_ctx=[0-9]{1,5}_[0-9]{1,5}$/"; http.user_agent; content:"Mozilla/5.0"; endswith; http.header_names; content:!"Referer|0d 0a|"; reference:url,www.cylance.com/en_us/blog/breaking-down-ff-rat-malware.html; classtype:command-and-control; sid:2024419; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_06_22, deployment Perimeter, performance_impact Moderate, confidence High, signature_severity Major, updated_at 2020_09_14;)