alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Beacon Activity"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".html?usersearch="; fast_pattern; http.cookie; content:"reg_fb_gate="; startswith; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/R"; http.header_names; content:!"Referer"; reference:url,twitter.com/z0ul_/status/1377385770470703106; reference:md5,c5668ee76cb9a9a5c4837eb0049c005b; classtype:trojan-activity; sid:2032360; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_04_01, deployment Perimeter, deployment SSLDecrypt, confidence Medium, signature_severity Major, tag c2, updated_at 2021_04_01, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)