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Comment by lilyball | Hacker News Reader

How does granting automation access to Finder allow other users to access Alice’s data? TCC doesn’t negate standard Unix file permissions, and other users couldnt read Alice’s data before TCC. And the standard user directories (such as Desktop) are not accessible by other users.

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... by manipulating the Finder to:

(1) Create a snapshot of the entire file system; (2) or find a recent Time Machine local snapshot; then (3) mount the snapshot obtained in [1] or [2] without owners enabled, effectively granting Alice read-only access to other people's files without having administrative privileges.

The Finder doesn’t create or mount APFS snapshots. And while I haven’t tested it, I fully expect Time Machine to still enforce Unix file permissions. You really need to be using the command line to do what you’re describing.

I haven’t tested the Finder case though. Nevertheless there is the `tell ‘Finder’ ... do shell script ... end tell` construct that _may_ be able to get the Finder to launch an arbitrary subprocess (and may inherit full disk access) just like how Terminal would.

However I’ve tested mounting a local snapshot using the Terminal having full disk access and found out that it is possible to mount a local snapshot and make the mounted copy ignore Unix file permissions.

It gives full sudo access.

Finder doesn’t run as sudo though. TCC is layered on top of Unix file permissions. It prohibits access to files, it doesn’t open a hole through pre-existing protections.

Basically, it acts as a sandbox rule. Sandboxing your app doesn’t allow you access to new files, it just denies access as determined by the sandbox profile.

I just took another look at the article and it appears I misunderstood what it was saying. I thought it was saying automation of Finder granted access to other users' files. This is not the case. It was talking about accessing other users' files in the previous section, but in this one it's merely claiming that allowing automation of Finder means being able to read data owned by your user that would otherwise be blocked by TCC.

And honestly, that's not a surprise. "Granting an app the ability to automate the Finder means granting it the ability to access any data the Finder can access" seems fairly obvious.

The article's point is that, while understandable, the UI completely hides these facts from you. Finder is not mentioned as having FDA in the settings app, and so, even if you realize that Automation of FDA app means having FDA, you won't be able to tell implicitly that apps having Automation of Finder rights also have FDA through this mechanism.

Furthermore, in principle there is nothing stopping OSX from giving me a prompt when Automation AppX without FDA access wants to access my files through Finder specifically.

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