alert tcp $EXTERNAL_NET [53, 443] -> $HOME_NET any (msg:"PROXY [PTsecurity] Bunitu FB set FB70820_1"; flow:established, to_client; dsize:50; content:"|00|"; offset:1; depth:1; stream_size:server, >,0; stream_size:server, <,52; stream_size:client, >,0; stream_size:client, <,16; flowbits:noalert; flowbits:isset, FB70820_0; flowbits:unset, FB70820_0; flowbits:set, FB70820_1; reference:url, rules.ptsecurity.com; classtype:trojan-activity; sid:11000340; rev:11;)