alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET HUNTING Base64 Encoded Server Response (success)"; flow:established,to_client; file.data; content:"c3VjY2Vzcw=="; startswith; classtype:bad-unknown; sid:2032883; rev:3; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2021_04_28, deployment Perimeter, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_13;)