alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET CURRENT_EVENTS [Fireeye] Backdoor.HTTP.BEACON.[CSBundle MSOffice GET]"; flow:established,to_server; content:"sess-="; content:"auth=0|3b|loc=US|7d|"; fast_pattern; http.method; content:"GET"; http.uri; pcre:"/^(?:\/updates|\/license\/eula|\/docs\/office|\/software-activation)/"; http.accept; content:"*/*"; http.accept_enc; content:"gzip, deflate, br"; startswith; http.accept_lang; content:"en-US"; bsize:5; reference:url,github.com/fireeye/red_team_tool_countermeasures; classtype:trojan-activity; sid:2031290; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_12_08, deployment Perimeter, confidence High, signature_severity Major, tag c2, updated_at 2020_12_09, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)