alert tcp $HOME_NET any -> $EXTERNAL_NET [1024:] (
msg:"ET MALWARE NanoCore RAT Keepalive 4";
flow:established,to_server;
dsize:84;
content:"|50 00 00 00|"; depth:4;
content:!"|00 00 00 00|"; within:4;
threshold:type both, track by_src, count 10, seconds 120;
flowbits:set,ET.NanoCore;
flowbits:noalert;
reference:md5,bf994dce3712fb66afa4a2ce5b3ceee4;
reference:url,medium.com/@the_abjuri5t/nanocore-rat-hunting-guide-cb185473c1e0;
classtype:trojan-activity;
sid:2046913; rev:3;
metadata:attack_target Client_Endpoint, created_at 2015_04_04, deployment Perimeter, malware_family NanoCore, performance_impact Moderate, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_07_26, former_sid 2810453;
)