alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Nitol.B Checkin"; flow:established,to_server; dsize:536<>1029; content:"|01 00 00 00|"; depth:4; content:!"|26|"; within:1; content:"|26|"; distance:1; within:1; content:"|26|"; distance:61; within:1; content:"|26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26|"; distance:204; within:20; content:"|26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26|"; distance:12; within:20; classtype:command-and-control; sid:2014601; rev:6; metadata:created_at 2012_04_17, malware_family Win32_Nitol_B, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_06;)