alert ftp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Kimsuky Related FTP File Download"; flow:established,to_server; content:"RETR|20|/board/"; fast_pattern; pcre:"/[a-z]{8}.(:?psd|dib)/Ri"; reference:url,github.com/eset/malware-ioc/tree/master/kimsuky/hotdoge_donutcat_case; classtype:trojan-activity; sid:2034690; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_12_13, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_12_13;)