alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"MALWARE [PTsecurity] Ursnif Malicious SSL Connection Detected"; flow:established, to_client; content:"|1703|"; depth:2; byte_test:2, >=,352, 1, relative; byte_test:2, <=,816, 1, relative; stream_size:server, >,1291; stream_size:server, <,3588; stream_size:client, >,987; stream_size:client, <,2356; flowbits:isset, FB449906_1; flowbits:unset, FB449906_1; threshold:type limit, track by_src, count 1, seconds 30; classtype:trojan-activity; metadata:created_at 2018_1_18; reference:url, github.com/ptresearch/AttackDetection; sid:11002452; rev:1;)