alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE Possible Locky AlphaNum Downloader Oct 3 2016"; flow:established,to_client; flowbits:isnotset,ET.http.binary; flowbits:isset,ET.LockyDL; http.header_names; to_lowercase; content:!"|0d 0a|cookie|0d 0a|"; content:!"|0d 0a|content-disposition|0d 0a|"; content:"|0d 0a|etag|0d 0a|"; http.content_len; bsize:6; content:"1"; fast_pattern; startswith; pcre:"/^1[6-8]\d{4}$/m"; file.data; content:!"MZ"; within:2; content:!"PK"; within:2; content:!"GIF"; within:3; content:!"|FF D8 FF|"; within:3; content:!"CWS"; within:3; content:!"ZWS"; within:3; pcre:"/^.{4}[\x0a-\x7f]{0,100}[\x00-x09\x80-\xff]/s"; classtype:trojan-activity; sid:2023316; rev:5; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2016_10_03, deployment Perimeter, malware_family Locky, confidence Medium, signature_severity Major, updated_at 2024_04_27;)