alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Possible Winnti TLS SNI Observed"; flow:established,to_server; tls.sni; content:".dnslookup.services"; nocase; isdataat:!1,relative; reference:url,www.welivesecurity.com/2020/01/31/winnti-group-targeting-universities-hong-kong/; classtype:targeted-activity; sid:2029344; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_01_31, deployment Perimeter, malware_family Winnti, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_01_31;)