alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Observed OSX/Silver Sparrow Download Domain in TLS SNI"; flow:established,to_server; tls_sni; content:"mobiletraits.s3.amazonaws.com"; bsize:29; reference:url,redcanary.com/blog/clipping-silver-sparrows-wings; classtype:domain-c2; sid:2031644; rev:1; metadata:affected_product Mac_OSX, attack_target Client_Endpoint, created_at 2021_02_22, deployment Perimeter, malware_family OSX_Silver, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_02_22, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)