Disabling Hotlink protection

Hello

I am using a CDN on the website but some aspects of it are unable to load because the security plugin is disabling image hotlinking. For example, the image

With the security plugin enabled shows access to the image is Forbidden: https://adv-adlps.netdna-ssl.com/wp-content/uploads/2016/12/email-marketing.jpg

With the security plugin disabled the image can be seen at the same path. My question is how to I turn that off or keep this function so that it works with the security plugin enabled?

Many thanks,

Allen