alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE MSIL/Agent.TRM Checkin Response"; flow:established,to_client; http.stat_code; content:"201"; http.start; content:"|0d 0a|Set-Cookie|3a 20|dkv="; fast_pattern; http.cookie; bsize:36; content:"dkv="; startswith; pcre:"/^[a-f0-9]{32}$/R"; reference:url,twitter.com/w3ndige/status/1247547923845578755; reference:md5,d2b81c4f5d075daa681f823cc9a5e4c0; classtype:command-and-control; sid:2029853; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_04_09, deployment Perimeter, deployment SSLDecrypt, malware_family MSIL_Agent_TRM, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_09;)