alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed StrongPity CnC Domain in TLS SNI"; flow:to_server,established; tls.sni; content:"app-system2-update.com"; endswith; reference:url,www.bitdefender.com/files/News/CaseStudies/study/353/Bitdefender-Whitepaper-StrongPity-APT.pdf; classtype:domain-c2; sid:2030413; rev:1; metadata:affected_product Web_Browsers, created_at 2020_07_01, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag StrongPity, tag SSL_TLS_SNI, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_07_01, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)