alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Darkshell.A Checkin XOR C0 Win XP"; flow:to_server,established; dsize:<512; content:"|e0 e0 e0 e0 97 89 8e 84 8f|"; content:"|98 90 e0|"; distance:2; within:3; classtype:command-and-control; sid:2018229; rev:2; metadata:created_at 2014_03_06, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)