alert http $HOME_NET any -> $EXTERNAL_NET 1024: (msg:"ET MALWARE Win32/Backdoor.Small.ao CnC Checkin"; flow:established,to_server; urilen:8; threshold:type limit, track by_dst, seconds 30, count 1; http.method; content:"POST"; http.uri; content:"/waiting"; fast_pattern; http.user_agent; content:"BC_Vic_"; depth:7; content:"BC_SPL"; endswith; http.header_names; content:"Expect"; content:!"Referer"; content:!"Accept"; content:!"Cache"; reference:md5,e8c9d8ffe8fae54b15262bf9aeb4172c; classtype:command-and-control; sid:2025370; rev:6; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_02_19, deployment Perimeter, malware_family Backdoor_Small, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_13;)