alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"MALWARE [PTsecurity] Win32/Spy.Ursnif.BK SSL connection"; flow:established, to_client; content:"|1703|"; depth:2; content:"|01B0|"; distance:1; within:2; fast_pattern; stream_size:server, >,1365; stream_size:server, <,2430; stream_size:client, >,1003; stream_size:client, <,1972; flowbits:isset, FB391441_1; flowbits:unset, FB391441_1; threshold:type limit, track by_src, count 1, seconds 30; classtype:trojan-activity; metadata:created_at 2017_11_14; reference:url, github.com/ptresearch/AttackDetection; sid:11002233; rev:1;)