A new category of apps is creating an added level of difficulty in the eternal cat-and-mouse game between kids and parents. These apps — often called “vault apps” — offer secret storage for photos, videos, chat programs, and even web browsers.

These apps are designed to look like normal calculators, games or utility folders. For example, calculator apps will be built with a functioning calculator as the door on top of the photo vault. When the user enters an access code through the calculator keypad, the storage area is unlocked.

Before we go over different ways to combat these apps, make sure to talk to teens about sharing inappropriate photos. While sending naughty pictures can seem like “no big deal” in today’s online world, it can have severe legal consequences, regardless of consent, for underage kids. Even if these kinds of photos don’t get kids in legal trouble, once a photo makes its way to the Internet, it will likely be online and available forever.

Here are a few strategies you can use to uncover and manage these kinds of apps.

Limit ability to download and install apps. One of the most effective (but drastic) ways to prevent kids from using these apps is to restrict app store access. You can read more about how restrictions for iOS devices work here.

Enable “Ask to Buy” on your family sharing plan for iOS devices. If completely limiting access will not be feasible, you can turn on Ask to Buy for each device in your iOS Family Sharing plan. This feature sends an approval notice to the family organizer for each download. The restriction applies to the App Store, iTunes, iBooks, in-app purchases, and iCloud storage.

Find hidden apps on iOS devices. This hack lets users make apps on iOS devices “disappear” from the main menu screen. There are two ways to find apps hidden with this technique. They will show up as a result in the search feature available by swiping all the way to the right past the home screen. You can also reboot the phone. A reboot returns all of the apps hidden with this method to the main screens.

Google, the Play Store, and iTunes will spill the beans. It may be time-consuming and create some grumbling about not trusting them, but reviewing all of the apps on your kid’s phone on a regular basis is the best way to stay on top of things. These apps depend on looking innocent at a glance, but that innocence will not survive a Google search or a review of the description in iTunes or the Play Store.

Check for camera permissions. New apps need to be given permission to access the camera on a device. Go into the settings menu, check out privacy settings for the camera to see which apps have camera access, and look for apps that don’t seem to belong.

Camouflage is the key to success for vault apps. Knowing what to look for is the first step in monitoring and managing these applications.