alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE SPEAR CnC Beacon 2"; flow:to_server,established; http.method; content:"GET"; http.uri; content:"?wd="; fast_pattern; pcre:"/\?wd=(?:[A-Za-z0-9_-]{4})*(?:[A-Za-z0-9_-]{2}==|[A-Za-z0-9_-]{3}=|[A-Za-z0-9_-]{4})$/"; http.header_names; content:!"Accept"; content:!"Referer|0d 0a|"; reference:url,blog.cylance.com/spear-a-threat-actor-resurfaces; reference:md5,1beb162fc327101c01b07240a924202f; classtype:command-and-control; sid:2021119; rev:4; metadata:attack_target Client_Endpoint, created_at 2015_05_20, deployment Perimeter, signature_severity Major, tag c2, updated_at 2020_10_01, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)