alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET CURRENT_EVENTS [Fireeye] Backdoor.SSL.BEACON.[CSBundle Ajax]"; flow:established,to_client; tls.cert_subject; content:"C=US, ST=WA, L=Seattle, O=Microsoft, OU=Information Technologies, CN=ajax.microsoft.com"; bsize:87; fast_pattern; tls.cert_issuer; content:"C=US, ST=WA, L=Seattle, O=Microsoft, OU=Information Technologies, CN=ajax.microsoft.com"; bsize:87; reference:url,github.com/fireeye/red_team_tool_countermeasures; classtype:trojan-activity; sid:2031299; rev:2; 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_08, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)