alert http1 $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE [Fireeye] Backdoor.BEACON M2"; flow:established,to_client; http.response_line; content:"HTTP/1."; startswith; http.header; content:"Server: nginx/1.14.0 (Ubuntu)"; content:"Connection|3a 20|close"; distance:0; content:"Cache-Control|3a 20|max-age=300, must-revalidate"; distance:0; content:"X-Content-Type-Options|3a 20|nosniff"; distance:0; content:"X-AspNetMvc-Version|3a 20|3.0"; fast_pattern; distance:0; content:"X-AspNet-Version|3a 20|4.0.30319"; distance:0; content:"X-Powered-By|3a 20|ASP.NET"; distance:0; content:"Content-Length|3a 20|"; content:"|0d 0a|"; distance:6; within:4; reference:url,www.fireeye.com/blog/threat-research/2020/12/evasive-attacker-leverages-solarwinds-supply-chain-compromises-with-sunburst-backdoor.html; classtype:trojan-activity; sid:2031321; rev:5; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_12_14, deployment Perimeter, confidence High, signature_severity Major, tag c2, updated_at 2024_04_14, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)