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Android: I don't need your permission

blog.danlew.net

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Re: Android: I don't need your permission

#11

Post by Fradow »

The theory seems great. The reality is not.

When you do that, you delegate your UX and proper functionning of your app to a third-party app.

The UX can vary according the app. One thing is certain, it won't always be consistent with your app. It is also going to be more complicated for the user (more actions to make, more choices, just because you don't want to add permissions).

The proper functionning is even worse. Did you ever heard about the fragmentation of Android? Well, Intents are where it's worse. Some apps plainly don't work, or are buggy.

Intents are great to save time prototyping something. However, if a feature is central to your app, you are better off ensuring yourself that it works well and is easy to use, something that Intents can't guarantee.

Of course, the permission system is far from ideal, and some people will not install your app because you ask for some permissions. I'd say that's a price to pay for developping on Android.

P.S.: some examples of Intents that don't work so well:

1) sending a mail. Good luck finding how to properly use an Intent that is not handled by text apps and allow you to put attachments

2) picking a photo from gallery and resize. A lot of photo apps are plain broken for that Intent. And I'm not talking about some obscure device on a rooted Android, I'm talking about Google's Nexus, with stock apps.

Re: Android: I don't need your permission

#12

Post by Someone1234 »

> If your app is closed-source then they have no way of verifying you're not downloading all their contacts to their servers.

That's a common fallacy. Even if it is open source someone could still be doing that. In order to be secure you would have to:

A) Download the source yourself B) Inspect the source C) Compile the source

Just because you have the source doesn't mean what you get from the Play Store/Amazon App store is 1:1 identical or even similar.

There is secret option D, have someone you trust do A through C and then give you the hash of the resulting compiled file. But two programs compiled on two machines often give different results due to library versions, compiler versions, environmental settings, and so on.

Re: Android: I don't need your permission

#13

Post by dozy »

CSDude wrote: post #10

This is the another reason I use CyanogenMod. It has Privacy Guard and I can disable the nasty permissions as I please. If you have Android 4.3+, you can also install it indivudally https://play.google.com/store/apps/details?id=com.findsdk.ap... (requires root I guess) The most helpful one, even if you are not privacy/security concerned is to disable wake up/keep awake requests, which Facebook and FB Messenger used i…

I love CyanogenMod (or at least the concept...I'm over dealing with the headache in practice), but the reason I used it was certainly not for improved stability and security.

Not that I particularly trust OEMs/carriers, but the only way I'd feel more secure with CyanogenMod is if I had time to audit the source and build the kernel and OS binaries myself, and that includes whatever code is used to root and unlock your device in the first place. If you do that though, more power to ya.

Also, disabling permissions at runtime is a foolproof way to make an app crash, as the vast majority of apps will assume they're granted the permissions hardcoded in the manifest at compile time.

One last point - rooting your phone and granting apps root access just to disable crucial permissions such as holding a wakelock seems pretty reckless - have you personally seen the source code for that app? At least the dev's website seems legit: http://www.findsdk.com/

EDIT: Even better, looks like the author of App Ops, or at least the owner if the findsdk.com domain, is in China :) https://who.is/whois/findsdk

Re: Android: I don't need your permission

#14

Post by foo2312 »

Someone1234 wrote: post #12

> If your app is closed-source then they have no way of verifying you're not downloading all their contacts to their servers. That's a common fallacy. Even if it is open source someone could still be doing that. In order to be secure you would have to: A) Download the source yourself B) Inspect the source C) Compile the source Just because you have the source doesn't mean what you get from the Play Store/Amazon App s…

It may seem a bit silly to add this, but I think it is good to link the reference for those who may not have seen it before:

Even compiling from source, one also has to trust the compiler...

(see, e.g. the classic http://cm.bell-labs.com/who/ken/trust.html, pdf version at https://www.ece.cmu.edu/~ganger/712.fall02/papers/p761-thomp...)

Re: Android: I don't need your permission

#15

Post by tjbiddle »

ctz wrote: post #8

The same goes for android.permission.INTERNET. Apps can open arbitrary URLs in the browser (which load without user intervention).

However that's not the only use case for android.permission.INTERNET - you need it for anything that does networking on the internet, such as API calls to your web application.

Re: Android: I don't need your permission

#16

Post by tormeh »

foo2312 wrote: post #14
Someone1234 wrote: post #12

> If your app is closed-source then they have no way of verifying you're not downloading all their contacts to their servers. That's a common fallacy. Even if it is open source someone could still be doing that. In order to be secure you would have to: A) Download the source yourself B) Inspect the source C) Compile the source Just because you have the source doesn't mean what you get from the Play Store/Amazon App s…

It may seem a bit silly to add this, but I think it is good to link the reference for those who may not have seen it before: Even compiling from source, one also has to trust the compiler... (see, e.g. the classic http://cm.bell-labs.com/who/ken/trust.html , pdf version at https://www.ece.cmu.edu/~ganger/712.fall02/papers/p761-thomp... )

And then you have to trust the OS. And the machine... Unless you build you computer yourself from silicon, you're not going to get rid of trust.

Re: Android: I don't need your permission

#17

Post by joshfraser »

Someone1234 wrote: post #12

> If your app is closed-source then they have no way of verifying you're not downloading all their contacts to their servers. That's a common fallacy. Even if it is open source someone could still be doing that. In order to be secure you would have to: A) Download the source yourself B) Inspect the source C) Compile the source Just because you have the source doesn't mean what you get from the Play Store/Amazon App s…

It's also easy to set up a man-in-the-middle proxy and watch the network traffic an app is sending.

Re: Android: I don't need your permission

#18

Post by mrpdaemon »

Someone1234 wrote: post #12

> If your app is closed-source then they have no way of verifying you're not downloading all their contacts to their servers. That's a common fallacy. Even if it is open source someone could still be doing that. In order to be secure you would have to: A) Download the source yourself B) Inspect the source C) Compile the source Just because you have the source doesn't mean what you get from the Play Store/Amazon App s…

The chain of trust doesn't quite stop at compiling the source, in order to be really sure that nothing unintended is going on you have to compile the compiler yourself. At the end of the day you will have to trust some bootstrapping binary compiler unless you put it together yourself in machine language.

Re: Android: I don't need your permission

#19

Post by aeroevan »

dozy wrote: post #13
CSDude wrote: post #10

This is the another reason I use CyanogenMod. It has Privacy Guard and I can disable the nasty permissions as I please. If you have Android 4.3+, you can also install it indivudally https://play.google.com/store/apps/details?id=com.findsdk.ap... (requires root I guess) The most helpful one, even if you are not privacy/security concerned is to disable wake up/keep awake requests, which Facebook and FB Messenger used i…

I love CyanogenMod (or at least the concept...I'm over dealing with the headache in practice), but the reason I used it was certainly not for improved stability and security. Not that I particularly trust OEMs/carriers, but the only way I'd feel more secure with CyanogenMod is if I had time to audit the source and build the kernel and OS binaries myself, and that includes whatever code is used to root and unlock your…

IIRC, Privacy Guard simply returns empty sets of data instead of just revoking the permissions so the app shouldn't crash. It probably will lose functionality, but by actively turning on PG you're signing up for that.

Re: Android: I don't need your permission

#20

Post by Groxx »

dozy wrote: post #13
CSDude wrote: post #10

This is the another reason I use CyanogenMod. It has Privacy Guard and I can disable the nasty permissions as I please. If you have Android 4.3+, you can also install it indivudally https://play.google.com/store/apps/details?id=com.findsdk.ap... (requires root I guess) The most helpful one, even if you are not privacy/security concerned is to disable wake up/keep awake requests, which Facebook and FB Messenger used i…

I love CyanogenMod (or at least the concept...I'm over dealing with the headache in practice), but the reason I used it was certainly not for improved stability and security. Not that I particularly trust OEMs/carriers, but the only way I'd feel more secure with CyanogenMod is if I had time to audit the source and build the kernel and OS binaries myself, and that includes whatever code is used to root and unlock your…

CyanogenMod's "deny permission" behavior is largely the same as XPrivacy's, but way less fine-grained (and way easier to use). Basically it just returns "empty" data for requests - it doesn't revoke the permission, because yes, that would cause crashes.

The vast majority of applications work with this with no problems. They just won't e.g. show your contacts.

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