alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE ArrobarLoader CnC Checkin M1"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php"; http.user_agent; content:"4RR0B4R 4 X0T4 D4 TU4 M4E"; fast_pattern; http.request_body; content:"0"; endswith; http.header_names; content:!"Referer"; content:!"Cache"; reference:md5,3d7436bcf635a7e56a785c9d26ed3767; classtype:command-and-control; sid:2026528; rev:5; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_02_07, deployment Perimeter, malware_family ArrobarLoader, performance_impact Low, confidence High, signature_severity Major, tag Loader, updated_at 2020_09_16;)