alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Observed Malicious SSL Cert (Cobalt Strike)"; flow:established,to_client; tls.cert_issuer; bsize:62; content:"C=DE, L=Germany, O=Kaspersky AO Lab., CN=*.me-en.kaspersky.com"; fast_pattern; reference:url,symantec-enterprise-blogs.security.com/blogs/threat-intelligence/buhti-ransomware; reference:md5,1104d60534143b8cf7a9a86c9cfe4601; reference:md5,6bb06ab176ae723bc901126f59e9243d; classtype:domain-c2; sid:2048311; rev:2; metadata:attack_target Client_Endpoint, created_at 2023_09_27, deployment Perimeter, deprecation_reason Age, malware_family Cobalt_Strike, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_12_26, reviewed_at 2023_12_26;)