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Can you trust that permission pop-up on macOS?

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Re: Can you trust that permission pop-up on macOS?

#181

Post by nmgycombinator »

josephg wrote: post #162
nmgycombinator wrote: post #122

Earlier quoted context omitted.

As someone who's looked into the internals of macOS for a bit now, this is all incredibly fascinating. However, I am curious: do you think capabilities could be implemented like this at a really low level? Part of me thinks we have the security models we do in POSIX is because they're simple enough to represent in C code. The capability systems you're mentioning sound cool, but they sound a lot more complex. And if t…

SeL4 is a capability based operating system toolkit, entirely implemented in C. The core operating system is just a few thousand lines of code. Its even mathematically proven to be bug free - which is totally insane. It even uses a capability to allocate (assign) memory. So you typically have a microservice (userland process) in charge of memory on the whole system. Other processes get heap memory allocated to them b…

I think Apple uses an L4 variant for their SEP co-processor, though I'm not sure if it's that specific one. Sounds like another OS I'll probably have to do a deep dive into at some point.

Re: Can you trust that permission pop-up on macOS?

#182

Post by pbhjpbhj »

throwaway290 wrote: post #166
cypherpunks01 wrote: post #78

Just recently learned I should be installing mac apps into my home directory Applications, not the system Applications (as every single app installer suggests). Of course, only makes sense for a single-user machine. If I downgrade myself to a non-admin user, and install apps into my home Applications, then I'm not bothered by permissions requests from apps to update themselves. Almost all of them can just do it, on t…

If you install an app in ~/Applications, it can auto update without root, but any sus code can overwrite it without root rights too

Which is madly insecure, right?

Re: Can you trust that permission pop-up on macOS?

#183

Post by SSLy »

nmgycombinator wrote: post #181
josephg wrote: post #162

Earlier quoted context omitted.

SeL4 is a capability based operating system toolkit, entirely implemented in C. The core operating system is just a few thousand lines of code. Its even mathematically proven to be bug free - which is totally insane. It even uses a capability to allocate (assign) memory. So you typically have a microservice (userland process) in charge of memory on the whole system. Other processes get heap memory allocated to them b…

I think Apple uses an L4 variant for their SEP co-processor, though I'm not sure if it's that specific one. Sounds like another OS I'll probably have to do a deep dive into at some point.

They also run L4 variants below and besides XNU, on same cores as the rest https://randomaugustine.medium.com/on-apple-exclaves-d683a2c...

Re: Can you trust that permission pop-up on macOS?

#184

Post by SSLy »

tonyedgecombe wrote: post #167
jen729w wrote: post #161

Earlier quoted context omitted.

Just so you know, there is something about dragging that app bundle to /Applications that causes something to happen. Because if you `mv` it in the terminal, the app often doesn't work. It's been a while since I did this, and I can't remember the details. Sorry. Someone else might.

There is a bit of magic going on in Finder with /Applications. It’s actually two folders, one in the system partition which you can’t write into and one in the data partition where anything you install goes.

There are three of them, two you've mentioned, and ~/Applications for each graphical user too.

Re: Can you trust that permission pop-up on macOS?

#185

Post by nmgycombinator »

SSLy wrote: post #183
nmgycombinator wrote: post #181

Earlier quoted context omitted.

I think Apple uses an L4 variant for their SEP co-processor, though I'm not sure if it's that specific one. Sounds like another OS I'll probably have to do a deep dive into at some point.

They also run L4 variants below and besides XNU, on same cores as the rest https://randomaugustine.medium.com/on-apple-exclaves-d683a2c...

Ooh! Thanks for the links!

Re: Can you trust that permission pop-up on macOS?

#187

Post by BetaMechazawa »

sureIy wrote: post #156
musicale wrote: post #142

Earlier quoted context omitted.

The passkey pop-ups which are indistinguishable from javascript pop-ups are a particularly egregious security mistake.

What's the problem here? Javascript popups can't read your fingerprint so what would be the endgame of a fake passkey popup?

timeout after 10 seconds "fingerprint can't be read, please enter password"

Re: Can you trust that permission pop-up on macOS?

#188

Post by nmgycombinator »

Alex_001 wrote: post #186

[dead]

I mean, as others have mentioned, actually true capabilities would be nice. But as long as we're going to have a database, it would have to end up in user space or in the kernel. And I'm not sure how much I like either option.

Re: Can you trust that permission pop-up on macOS?

#189

Post by throwaway290 »

pbhjpbhj wrote: post #182
throwaway290 wrote: post #166

Earlier quoted context omitted.

If you install an app in ~/Applications, it can auto update without root, but any sus code can overwrite it without root rights too

Which is madly insecure, right?

I think so, somebody correct me if I'm wrong. Maybe if SIP is on and untrusted software is disabled then it would be caught, but if you have xcode then sus code can also probably sign whatever it created.

/Applications seems defense in depth for developer machines that often run untrusted code. Apps ask for admin to update & then I can deny it and go check the official site and stuff for download later

Re: Can you trust that permission pop-up on macOS?

#190

Post by jeroenhd »

matthewfcarlson wrote: post #126
matthewfcarlson wrote: post #125

Earlier quoted context omitted.

What is the threat model of clicking on a fake popup? Isn't it a no-op because it isn't actually coming from the system?

Just realized that it asked for your system password if you don't have Touch ID.

Having Touch ID does not immediately make all password popups disappear. I think it may be because of MDM/security settings my company puts on my work macbook, but now I get the joy of password prompts that sometimes work with Touch ID and other times demand a password.

I prefer UAC over whatever the hell Apple is doing. I've had days where I close my applications after a day of work and find two or three password prompts just hovering in the background. Were they important? Should I still permit them? Who knows!

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