alert tcp $HOME_NET any -> $EXTERNAL_NET 1024:65535 (msg:"ET MALWARE Bandook v1.35 Keepalive Reply"; flowbits:isset,BE.Bandook1.35; flow:established,to_server; dsize:9; content:"|cf ab a8 a4 ae cf 26 26 26|"; offset:0; reference:url,www.nuclearwintercrew.com; reference:url,research.sunbelt-software.com/threatdisplay.aspx?name=Bandook&threatid=40408; classtype:trojan-activity; sid:2003557; rev:5; metadata:created_at 2010_07_30, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)