alert ftp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Malicious XSL file download (FTP)"; flow:established,to_server; content:"RETR|20|/frog/usoprive.xsl"; fast_pattern; reference:md5,dd0124264f131a203ecfc70314dcec04; reference:url,asec.ahnlab.com/ko/19439/; classtype:trojan-activity; sid:2031482; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_01_05, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_01_05;)