alert tls $EXTERNAL_NET any -> $HOME_NET any (
msg:"ET MALWARE Observed Malicious SSL Cert (Cobalt Strike CnC)";
flow:established,to_client;
tls.cert_subject;
content:"C=Zhongguo, ST=Internet Security, L=ShenZhen, O=ESET, OU=Internet Security, CN=Eset Internet Security"; bsize:101; fast_pattern;
tls.cert_issuer;
content:"C=Zhongguo, ST=Internet Security, L=ShenZhen, O=ESET, OU=Internet Security, CN=Eset Internet Security"; bsize:101;
reference:url,twitter.com/bryceabdo/status/1308802052487774210;
classtype:domain-c2;
sid:2030901; rev:1;
metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_and_Server, created_at 2020_09_23, deployment Perimeter, malware_family Cobalt_Strike, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_23, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;
)