Step 1: Create a Custom URL Category for Allowed File Types
This category will define the image and audio MIME types that should be excluded from the block rule.
1. Navigate to Zero Trust Secure Access → Secure Access Resources → Custom URL Categories.
2. Click Add.
3. Enter a unique and descriptive name for the category (e.g., WhatsApp-Allowed-Media).
4. Under Match Mode, select Domain match. Domain match will match URLs from the specified domains along with all relevant subdomains.
5. In the domain entry field, add the following MIME-type-based domain entries, separating each with a space:
- mms/image
- mms/audio
6. Click Add to apply the entries.
7. Click Save.
Step 2: Create the Internet Access Rule
1. Navigate to Zero Trust Secure Access → Secure Access Rules → Internet Access.
2. Click Create Rule.
3. Enter a unique Name for the rule (e.g., Block WhatsApp File Transfers - Except Media).
4. Add an optional Description and ensure Status is set to Enabled.
Configure Rule Parameters
Source
- Under Users / Groups, select the specific user this rule should apply to.
Traffic
- Under URLs/Cloud Apps, click to add a cloud app filter.
- Search for and select WhatsApp as the target cloud application.
- Select the cloud app actions to target:
- Upload file
- Download file
Under Exclude the following Custom URL Categories, select the custom category created in Step 1 (WhatsApp-Allowed-Media). This exclusion ensures that requests matching the mms/image and mms/audio MIME types are not subject to the block action.
Action
- Under Access Control, select Block Cloud App / URL Access.
This action blocks access to the specified cloud app traffic and logs the activity in the Secure Access History screen.
5. Click Save.
Validate the rule by attempting to upload and download various file types via WhatsApp Web. Image and audio files should transfer successfully, while all other file types should be blocked.
If the issue persists, please contact the TrendAI support team for further assistance.