alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO .exe download with no referer (noalert)"; flow:established,to_server; flowbits:set,exe.no.referer; flowbits:noalert; http.uri; content:".exe"; fast_pattern; http.header_names; content:!"Referer|0d 0a|"; classtype:bad-unknown; sid:2020573; rev:5; metadata:created_at 2015_02_27, performance_impact Moderate, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_22;)