alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Trickbot Checkin Response"; flow:established,to_client; http.stat_code; content:"200"; http.content_type; content:"text/plain"; bsize:10; http.header; content:"Content-Length|3a 20|3|0d 0a|"; fast_pattern; nocase; file.data; content:"/1/"; depth:3; endswith; reference:md5,5d2d59d6cbff1dc1d108bdcae0294c51; classtype:command-and-control; sid:2032218; rev:6; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_02_15, deployment Perimeter, malware_family TrickBot, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_05_19;)