alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MOBILE_MALWARE SSL/TLS Certificate Observed (Betcity CnC)"; flow:established,to_client; tls.cert_subject; content:"CN=*.boxberry1.ru"; bsize:17; fast_pattern; tls.cert_issuer; content:"C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3"; bsize:52; reference:url,twitter.com/ReBensk/status/1259146097978564609; classtype:domain-c2; sid:2030150; rev:1; metadata:affected_product Android, attack_target Mobile_Client, created_at 2020_05_11, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_05_11;)