alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Nitol.A Checkin"; flow:from_client,established; dsize:1028; content:"|01 00 00 00|"; depth:4; content:!"|00|"; within:1; content:"|00|"; distance:1; within:1; content:"|00|"; distance:61; within:1; content:"|00 00 00 00 00|Windows|20|"; fast_pattern; distance:0; content:"|00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|"; distance:0; content:"|00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|"; distance:12; within:20; classtype:command-and-control; sid:2014600; rev:7; metadata:created_at 2012_04_17, malware_family Win32_Nitol_A, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_19;)