alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET RETIRED Observed TWISTEDPANDA Domain in TLS SNI (img .elliotterusties .com)"; flow:established,to_server; tls.sni; content:"img.elliotterusties.com"; bsize:23; fast_pattern; reference:url,research.checkpoint.com/2022/twisted-panda-chinese-apt-espionage-operation-against-russians-state-owned-defense-institutes/; classtype:targeted-activity; sid:2036662; rev:2; metadata:attack_target Client_Endpoint, created_at 2022_05_23, deployment Perimeter, former_category MALWARE, malware_family TwistedPanda, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, updated_at 2024_09_12, reviewed_at 2024_09_12, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)