alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE CryptoBot Downloading Files"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"btc"; fast_pattern; pcre:"/\/[a-z]+\.k(?:ey)?btc$/"; http.header_names; content:!"Referer|0d 0a|"; reference:url,kernelmode.info/forum/viewtopic.php?f=16&t=3563; classtype:trojan-activity; sid:2019607; rev:4; metadata:created_at 2014_10_30, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_25;)