You can't trust macOS Privacy and Security settings

In this Friday’s magic demonstration, I’m going to show how what you see in Privacy & Security settings can be misleading, when it tells you that an app doesn’t have access to a protected folder, but it really does.

Although it appears you can achieve this using several ordinary apps, to make things simpler and clearer I’ve written a little app for this purpose, Insent, available from here: insent11

I’m working in macOS Tahoe 26.4, but I suspect you should see much the same in any version from macOS 13.5 onwards, as supported by Insent.

For this magic demo, I’m only going to use two of Insent’s six buttons:

Open by consent, which results in Insent choosing a random text file from the top level of your Documents folder, and displaying its name and the start of its contents below. As it does this without involving the user in the process, the macOS privacy system TCC requires it to obtain the user’s consent to list and access the contents of that protected folder.Open from folder, which opens an Open and Save Panel where you select a folder. Insent then picks a random text file from the top level of that folder, and displays its name and the start of its contents below. Because you expressed your intent to access that protected folder, TCC considers that is good enough to give access without requiring any consent.

Demonstration

Once you have downloaded Insent, extracted it from its archive, and dragged the app from that folder into one of your Applications folders, follow this sequence of actions:

• Open Insent, click on Open by consent, and consent to the prompt to allow it to access your Documents folder. Shortly afterwards, Insent will display the opening of one of the text files in Documents. Quit Insent.
• Open Privacy & Security settings, select Files & Folders, and confirm that Insent has been given access to Documents.
• Open Insent, click on Open by consent, and confirm it now gains access to a text file without asking for consent. Quit Insent.
• Open Privacy & Security settings, select Files & Folders, and disable Documents access in Insent’s entry there using the toggle.
• Open Insent, click on Open by consent, and confirm that it can no longer open a text file, but displays [Couldn't get contents of Documents folder].
• Click on Open from folder and select your Documents folder there. Confirm that works as expected and displays the name and contents of one of the text files in Documents.
• Click on Open by consent, and confirm that now works again.
• Confirm that Documents access for Insent is still disabled in Files & Folders.
• Whatever you do now, the app retains full access to Documents, no matter what is shown or set in Files & Folders.

Indeed, the only way you can protect your Documents folder from access by Insent is to run the following command in Terminal:

tccutil reset All co.eclecticlight.Insent

then restart your Mac. That should set Insent’s privacy settings back to their default.

How does this work?

Insent is an ordinary notarised app, and doesn’t run in a sandbox or pull any clever tricks. When System Integrity Protection (SIP) is enabled some of its operations are sandboxed, though, including attempts to list or access the contents of locations that are protected by TCC.

When you click on its Open by consent button, sandboxd intercepts the File Manager call to list the contents of Documents, as a protected folder. It then requests approval for that from TCC. If that’s given, the access is granted.

If you then disable Insent’s access to Documents in Privacy & Security settings, TCC denies access to Documents, and Insent can’t get the list of its contents.

If you then access Documents by intent through the Open and Save Panel, sandboxd no longer intercepts the request, and TCC therefore doesn’t grant or deny access. Thus, access to a protected folder by user intent changes the sandboxing applied to the caller by removing its constraint to that specific protected folder. As the sandboxing isn’t controlled by or reflected in Privacy & Security settings, that allows TCC to continue showing access restrictions that aren’t applied because the sandbox isn’t applied.

Conclusion

Access restrictions shown in Privacy & Security settings, specifically those to protected locations in Files & Folders, aren’t an accurate or trustworthy reflection of those that are actually applied. It’s possible for an app to have unrestricted access to one or more protected folders while its listing in Files & Folders shows it being blocked from access, or for it to have no entry at all in that list.