alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Observed Default CobaltStrike SSL Certificate"; flow:established,to_client; tls.cert_issuer; content:"C=Earth"; nocase; content:"ST=Cyberspace"; nocase; content:"L=Somewhere"; nocase; content:"O=cobaltstrike"; nocase; content:"OU=AdvancedPenTesting"; nocase; content:"CN=Major Cobalt Strike"; nocase; fast_pattern; reference:url,fireeye.com/blog/threat-research/2020/03/the-cycle-of-adversary-pursuit.html; classtype:trojan-activity; sid:2030111; rev:2; metadata:attack_target Client_Endpoint, created_at 2020_05_06, deployment Perimeter, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2021_08_26;)