alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Dark Halo/SUNBURST CnC Domain (lcomputers .com in TLS SNI)"; flow:established,to_server; tls.sni; dotprefix; content:".lcomputers.com"; endswith; fast_pattern; reference:url,www.volexity.com/blog/2020/12/14/dark-halo-leverages-solarwinds-compromise-to-breach-organizations/; classtype:trojan-activity; sid:2031395; rev:1; metadata:attack_target Client_Endpoint, created_at 2020_12_15, deployment Perimeter, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_12_15, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)