alert tcp $HOME_NET any -> $EXTERNAL_NET [53, 443] (msg:"PROXY [PTsecurity] Bunitu FB set FB70820_0"; flow:established, to_server; dsize:14; content:"|00|"; offset:1; depth:1; stream_size:server, >,0; stream_size:server, <,2; stream_size:client, >,0; stream_size:client, <,16; flowbits:noalert; flowbits:set, FB70820_0; reference:url, rules.ptsecurity.com; classtype:trojan-activity; sid:11000339; rev:12;)