alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Linux/Moose NAT Traversal CnC Beacon - Sleep"; flow:established,from_server; dsize:8; content:"|16 00|"; depth:2; content:!"|04 00|"; within:2; content:!"|00 00|"; within:2; content:!"|00|"; distance:2; within:1; content:!"|00|"; distance:5; within:1; flowbits:isset,ET.Linux.Moose; reference:url,welivesecurity.com/wp-content/uploads/2015/05/Dissecting-LinuxMoose.pdf; classtype:command-and-control; sid:2021151; rev:2; metadata:attack_target Client_Endpoint, created_at 2015_05_26, deployment Perimeter, signature_severity Major, tag c2, updated_at 2019_07_26, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)