alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Buer Loader Download Request"; flow:established,to_server; urilen:>200; flowbits:set,ETPRO.wacatac.b.download; http.method; content:"GET"; http.uri; content:"/api/download/"; depth:14; fast_pattern; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/R"; http.header_names; content:!"Accept"; content:!"Referer"; reference:md5,a8819db1fa758fd9f1d501dbb50f454f; classtype:command-and-control; sid:2029078; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_11_12, deployment Perimeter, malware_family BuerLoader, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_02_11;)