alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET HUNTING robots Request Returning Base64 (Inbound)"; flow:established,to_client; flowbits:isset,ET.robots; http.stat_code; content:"200"; fast_pattern; file.data; pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/"; classtype:bad-unknown; sid:2044539; rev:1; metadata:attack_target Client_Endpoint, created_at 2023_03_09, deployment Perimeter, performance_impact Significant, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_03_09; target:dest_ip;)