alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed RMM Domain in TLS SNI (a1-backend-packages-* .s3 .amazonaws .com)"; flow:established,to_server; tls.sni; dotprefix; content:"a1-backend-packages"; fast_pattern; content:".s3.amazonaws.com"; endswith; distance:0; reference:url,attack.mitre.org/techniques/T1219/; reference:url,action1.com/documentation/firewall-configuration/; classtype:misc-activity; sid:2063878; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, affected_product Windows_8, affected_product Windows_10, affected_product Action1, attack_target Client_and_Server, created_at 2025_08_01, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag RAT, tag RemoteAccessTool, updated_at 2025_08_01, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1219, mitre_technique_name Remote_Access_Software;)