alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE GoBrut/StealthWorker Service Bruter CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/knock?worker="; fast_pattern; content:"&os="; content:"&version="; http.user_agent; content:"Mozilla/5.0 (X11|3b 20|Ubuntu|3b 20|Linux x"; startswith; http.accept_enc; content:"gzip"; startswith; endswith; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; reference:md5,bcb7d4fdee2023ad62132ebdf794baa4; reference:url,blog.yoroi.company/research/gobrut-a-new-golang-botnet/; reference:url,blog.yoroi.company/research/new-gobrut-version-in-the-wild/; classtype:command-and-control; sid:2033719; rev:6; metadata:affected_product Linux, attack_target Client_Endpoint, created_at 2019_05_22, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, updated_at 2024_05_01;)