alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Backdoor.Win32.Svlk Server Reply"; flow:from_server,established; dsize:44; content:"|33 39 0d ff 0a c4 e5 9f d5 ec 58 4a 69|"; depth:13; reference:md5,c929e8c75901c7e50685df0445a38bd0; classtype:trojan-activity; sid:2013892; rev:1; metadata:created_at 2011_11_09, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)