alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"MALWARE [PTsecurity] Win32/Lethic.AF"; flow:established, to_server; dsize:6; stream_size:server, <,40; stream_size:client, <,26; content:"|0021|"; offset:3; depth:2; flowbits:isset, FB663513_1; flowbits:unset, FB663513_1; classtype:trojan-activity; metadata:created_at 2018_08_26; reference:url, github.com/ptresearch/AttackDetection; sid:11003610; rev:1;)