alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Observed Malicious SSL Cert (Ursnif CnC)"; flow:established,to_client; tls.cert_subject; bsize:14; content:"CN=avas1ta.com"; fast_pattern; reference:md5,471d596dad7ca027a44b21f3c3a2a0d9; classtype:command-and-control; sid:2046616; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2023_06_22, deployment Perimeter, malware_family ursnif, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_06_22;)