alert tcp $HOME_NET any -> $EXTERNAL_NET [1024:] (msg:"ET MALWARE NanoCore RAT Keepalive 1"; flow:established,to_server; flowbits:set,ET.NanoCore; flowbits:noalert; content:"|08 00 00 00|"; depth:4; content:!"|00 00 00 00|"; within:4; threshold:type both, track by_src, count 10, seconds 120; reference:md5,8d7e60651330c674cccecc37415c4905; reference:url,medium.com/@the_abjuri5t/nanocore-rat-hunting-guide-cb185473c1e0; classtype:trojan-activity; sid:2046907; rev:3; metadata:attack_target Client_Endpoint, created_at 2015_03_27, deployment Perimeter, malware_family NanoCore, performance_impact Moderate, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_14, former_sid 2810288;)