alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Possible UNC1878 Cobalt Strike CnC SSL Cert Inbound (Mountainvew)"; flow:established,to_client; tls.cert_subject; content:", L=Mountainvew, "; nocase; fast_pattern; tls.cert_issuer; content:", L=Mountainvew, "; nocase; reference:md5,5c1fce8fa3e228b8f2641bb1f7a29c3f; reference:url,www.youtube.com/watch?v=BhjQ6zsCVSc; reference:url,gist.github.com/aaronst/6aa7f61246f53a8dd4befea86e832456; classtype:targeted-activity; sid:2031136; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_10_29, deployment Perimeter, malware_family Cobalt_Strike, performance_impact Low, confidence Medium, signature_severity Major, tag SSL_Suspicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_10_29;)