alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"REMOTE [PTsecurity] DarkTrack"; flow:established, to_server; dsize:6; content:"|0000 00|"; fast_pattern; offset:2; depth:3; content:"|01|"; offset:0; depth:1; byte_test:1,>,0x10,1; byte_test:1,<,0xf0,1; stream_size:server, <, 3; stream_size:client, =, 7; reference:url, rules.ptsecurity.com; classtype:trojan-activity; sid:10000431; rev:12;)