vBulletin Manual - Managing Attachment Permissions

Managing your attachment permissions is similar to editing global usergroup permissions, but allows more control. If you click Attachments > Attachment Permissions, you will see a screen similar to this:

Here, you will see each attachment extension on your forum with a list of all usergroups under each extension. Notice the color key at the top. In this example, red indicates that a usergroup has a custom attachment permission specified for this forum. No attachment permission has been specified, so the group will be using the default attachment extension permissions.

Next to each extension, you will see 2 links:

Reset – this will automatically delete any custom permissions that were set for this extension.
Deny All – this will automatically deny every usergroup access to upload this extension. This is helpful if you want to deny access to an extension for most groups

To edit or add an attachment permission, simply find the appropriate extension and usergroup, and click [Edit]. This will lead you to this screen:

If you are unsure of what a specific option does, click the inline help icon for more information.

Note:

Make sure Use Custom Permissions is selected at the top of the page if you want your changes to be saved.