alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Beacon Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; bsize:13; content:"/copyright.js"; fast_pattern; http.cookie; content:"SSID="; startswith; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/R"; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; reference:md5,653b45c576c89c00a164b51e23732957; classtype:trojan-activity; sid:2032337; rev:3; metadata:attack_target Client_Endpoint, created_at 2021_03_26, deployment Perimeter, confidence Medium, signature_severity Major, tag c2, updated_at 2024_04_30, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)