alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Observed Malicious SSL Cert (JS/Ostap CnC)"; flow:established,to_client; tls.cert_subject; content:"CN=pro100zver.mskhost.pro"; nocase; reference:md5,f5cf9ca73dd30caf43d75dd19240a79e; classtype:domain-c2; sid:2030602; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_and_Server, created_at 2020_07_28, deployment Perimeter, malware_family Ostap, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_07_28, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)