alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE SPEAR CnC Beacon"; flow:to_server,established; http.method; content:"GET"; http.uri; content:".asp?"; fast_pattern; pcre:"/\.asp\?(?:[A-Za-z0-9+*]{4})*(?:[A-Za-z0-9+*]{2}==|[A-Za-z0-9+*]{3}=|[A-Za-z0-9+*]{4})$/"; http.user_agent; content:"|20|MSIE|20|"; http.header_names; content:!"Accept"; content:!"Referer|0d 0a|"; reference:url,blog.cylance.com/spear-a-threat-actor-resurfaces; reference:md5,a69ac85c7e723ae37377516d7054fa0b; classtype:command-and-control; sid:2021118; rev:6; metadata:attack_target Client_Endpoint, created_at 2015_05_20, deployment Perimeter, performance_impact Moderate, signature_severity Major, tag c2, updated_at 2024_04_22, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)