I thought granting internet access to apps is not avoidable on Android.
When an app does not request internet, is it really guaranteed that it cannot talk to the outside world? Or is it having other avenues like opening a browser or some other component with a custom url or something?
Update: I just asked Gemini, and it does not look good:
An Android app without the INTERNET permission is not guaranteed to be isolated from the outside world. While it cannot make direct network connections itself, it can use several other mechanisms to transmit data externally:
Intent-Based Communication (The Browser) An app can launch an explicit or implicit Intent to hand data over to another app that does have internet access.
That means the app can open a system browser using a URL containing the data it wants to transmit.
It can also load a Chrome Custom Tab inside its own UI task, passing data through the URL string.
There is also Inter-Process Communication: If two apps from the same developer share a User ID (sharedUserId), they run in the same process and share all permissions, including internet access.
There is also the concept of Content Providers: Content Providers allow apps to share data. An offline app can write data into a shared database or a public Content Provider. A secondary, online-enabled app can then read that database and upload the contents.
I guess that makes sense. Since most non-privacy-focused Android distributions don't let users turn off the internet permission, keeping the permission secure likely ceased to be a priority.
The full list of bypasses is likely much larger because it doesn't fall in the scope of bug bounties.
You don’t need internet to run JS though. And the JS seems to be pretty sandboxed in normal viewers too, so a pdf file shouldn’t make network requests on its own. As long as there is no iframe-like content I don’t see how rendering a document would ever need network.
This is interesting.
I thought granting internet access to apps is not avoidable on Android.
When an app does not request internet, is it really guaranteed that it cannot talk to the outside world? Or is it having other avenues like opening a browser or some other component with a custom url or something?
Update: I just asked Gemini, and it does not look good:
An Android app without the INTERNET permission is not guaranteed to be isolated from the outside world. While it cannot make direct network connections itself, it can use several other mechanisms to transmit data externally:
Intent-Based Communication (The Browser) An app can launch an explicit or implicit Intent to hand data over to another app that does have internet access.
That means the app can open a system browser using a URL containing the data it wants to transmit.
It can also load a Chrome Custom Tab inside its own UI task, passing data through the URL string.
There is also Inter-Process Communication: If two apps from the same developer share a User ID (sharedUserId), they run in the same process and share all permissions, including internet access.
There is also the concept of Content Providers: Content Providers allow apps to share data. An offline app can write data into a shared database or a public Content Provider. A secondary, online-enabled app can then read that database and upload the contents.
You're aware that the only really secure computing device has no way to connect to a network and is under armed guard?
I guess that makes sense. Since most non-privacy-focused Android distributions don't let users turn off the internet permission, keeping the permission secure likely ceased to be a priority.
The full list of bypasses is likely much larger because it doesn't fall in the scope of bug bounties.
Christ that's depressing.
I'm assuming that all works even with application sandboxing (1) or am I mis-reading how that is applied to applications.
Man I need to move my movement to GrapheneOS up to be sooner.
(1) https://source.android.com/docs/security/app-sandbox
Tried it and I love it. Good work! Have you considered hosting it on F-Droid?
Sounds great! You'll just need your social security or passport id sent to google to install and use it... sobs
Seems nice, will check it out. I liked this one as well: "Little File Explorer – File Manager for Android 1.0 and above" 28.dec.2023 https://news.ycombinator.com/item?id=38789958
Can you add odt, ods, etc support? I use libreoffice viewer but it would be nice to reduce the number of apps on my device.
Since everything is offline, what ended up being the hardest format to support while keeping rendering faithful?
Why would rendering a document need internet access?
PDFs can do all sorts of shenanigans, such as bundle executable javascript that runs when the file is opened.
You don’t need internet to run JS though. And the JS seems to be pretty sandboxed in normal viewers too, so a pdf file shouldn’t make network requests on its own. As long as there is no iframe-like content I don’t see how rendering a document would ever need network.
Nice idea