Have you ever tried to install an app, only to get a message saying the app wants to access your contacts? Do you know why the app needs such access? Are you violating the duty of confidentiality by providing access to your clients contact information? If the app won't install unless you allow access to the contacts, do you need client consent to install the app?
Here is an interesting article on the subject. The article also relates to the duty of competence about technology.