alert tcp $HOME_NET any -> $EXTERNAL_NET !$HTTP_PORTS (msg:"ET MALWARE [PTsecurity] Backdoor.Win32/Remcos RAT pkt checker 4"; flow:established, to_server; stream_size:server,<,70; stream_size:client,<,696; stream_size:client,>,0; stream_size:server,>,35; flowbits:isset,FB180732_3; flowbits:unset,FB180732_3; threshold:type limit,track by_src,count 1, seconds 30; reference:url,blog.fortinet.com/2017/02/14/remcos-a-new-rat-in-the-wild-2; classtype:trojan-activity; sid:2024698; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_09_11, deployment Perimeter, malware_family Remcos, performance_impact Moderate, confidence Medium, signature_severity Major, updated_at 2020_11_06;)