alert tcp $HOME_NET any -> $EXTERNAL_NET 1024: (msg:"ET MALWARE CoreDDRAT KeepAlive Message"; flow:established,to_server; content:"|74 69 6d 65 2f 44 44 48 63 6b 2f 2e|"; startswith; fast_pattern; content:"|2d 48 63 6b|"; isdataat:!1,relative; threshold:type limit, track by_src, count 1, seconds 600; reference:md5,f3b3013101e1ae9b0e0ec709f3341cb9; reference:url,twitter.com/pmelson/status/1241914864853008384; classtype:command-and-control; sid:2029726; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_03_23, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, updated_at 2020_03_23;)