alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"REMOTE [PTsecurity] Babylon"; flow:established, to_client; dsize:4; content:"|FF|"; offset:1; depth:1; content:"|FF|"; distance:1; within:1; stream_size:server, <,124; stream_size:client, >,5; stream_size:client, <,250; flowbits:isset, FB322496_1; flowbits:unset, FB322496_1; reference:url, rules.ptsecurity.com; classtype:trojan-activity; sid:11001785; rev:6;)