alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE DDoS.Win32/Nitol.B Checkin"; flow:established,to_server; dsize:>1000; content:"|88 88 08 00|"; depth:4; fast_pattern; content:"|2E|"; distance:1; within:1; content:"|2F 73|"; distance:2; within:2; content:"|00 00 00 00 00 00 00 00|"; within:15; reference:md5,f078e099b1f8afc7c43eb05b4badf9e7; classtype:command-and-control; sid:2021111; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2015_05_16, deployment Perimeter, malware_family Nitol_DDoS, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_19;)