alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Blacknix CnC Checkin"; flow:to_server,established; dsize:200<>300; content:"|32|"; depth:1; content:"|7c 78 01|"; distance:2; within:3; pcre:"/^[0-9]{3}\x7cx/"; reference:md5,b4e95d3ec39cf8c7347ca1c64cfed631; classtype:command-and-control; sid:2027731; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_07_19, deployment Perimeter, malware_family Win32_Blacknix, confidence High, signature_severity Major, tag Blacknix, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)