alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE ArtraDownloader CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"dwnack.php?cId="; fast_pattern; http.header_names; content:!"Referer"; reference:url,unit42.paloaltonetworks.com/multiple-artradownloader-variants-used-by-bitter-to-target-pakistan/; classtype:command-and-control; sid:2026985; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_02_26, deployment Perimeter, malware_family ArtraDownloader, performance_impact Low, confidence High, signature_severity Major, tag Patchwork, tag DonotGroup, updated_at 2020_08_27;)