This article describes how to deny uploading images, documents, or videos in WhatsApp web conversation by using the application control signature.
In order to control web WhatsApp upload traffic that would require enabling SSL deep inspection + application control profile in the firewall policy.
Step 1: Go to Security Profiles > Application Control.
Step 2: Select the Profile Name.
Step 3: Select the Edit.
Step 4: Inside the profile, go to Application and Filter Overrides.
Step 5: Select the Create New.
Step 6: Go to Action Block.
Step 7: Search for application signature: WhatsApp_Web_File.Upload.
Step 8: Right-click and + Add Selected.
Step 9: Enable QUIC protocol option with an action block.
Step 10: Use application control profile in the firewall policy with SSL deep inspection.