Permissions are a means of controlling and regulating access to specific system- and device-level functions by software. Typically, types of permissions cover functions that may have privacy implications, such as the ability to access a device's hardware features, and personal data. Permissions are typically declared in an application's manifest, and certain permissions must be specifically granted at runtime by the user—who may revoke the permission at any time. Permission systems are common on mobile operating systems, where permissions needed by specific apps must be disclosed via the platform's app store.
The ability to "overlay" themselves within other apps.
Installing, deleting and otherwise managing applications.
Authentication tokens of web services stored in system storage for sharing between apps.
Prior to Android 6.0 "Marshmallow", permissions were automatically granted to apps at runtime, and they were presented upon installation in Google Play Store. Since Marshmallow, certain permissions now require the app to request permission at runtime by the user. These permissions may also be revoked at any time via Android's settings menu. Usage of permissions on Android are sometimes abused by app developers to gather personal information and deliver advertising; in particular, apps for using a phone's camera flash as a flashlight have been known to require a large array of unnecessary permissions beyond what is actually needed for the stated functionality. iOS imposes a similar requirement for permissions to be granted at runtime, with particular controls offered for enabling of Bluetooth, Wi-Fi, and location tracking.
WebPermissions
WebPermissions is a permission system for web browsers. When a web application needs some data behind a permission, it must request it first. When it does it, a user sees a window asking him to make a choice. The choice is remembered, but can be cleared lately. Currently the following resources are controlled:
* audio capturing devices, like soundcards, and their model names and characteristics
* video capturing devices, like cameras, and their identifiers and characteristics
Analysis
The permission-based access control model assigns access privileges for certain data objects to apps. This is a derivate of the discretionary access control model. The access permissions are usually granted in the context of a specific user on a specific device. Permissions are granted permanently with few automatic restrictions. In some cases permissions are implemented in 'all-or-nothing' approach: a user either has to grant all the requested permissions to an app, or be unable to use the app. It remains intransparent to the user when the permission is used by a program or app to access the data protected by the permission access control mechanism. Even if a user can revoke a permission, the app can blackmail a user by refusing to operate, for example by just crashing. The permission mechanism has been widely criticized by researchers for several reasons, including;
Intransparency of personal data extraction and surveillance, including the creation of a false sense of security;
End-user fatigue of micro-managing access permissions leading to a fatalistic acceptance of surveillance and intransparency;
Massive data extraction and personal surveillance carried out once the permissions are granted.
There are some solutions, such as XPrivacy, which instead of providing access to the requested data instead of throwing an exception and crashing an app returning disinformation to make an app operate as if the permission was granted. Mockdroid is another instance of this approach. It is also possible to use static analysis to analyze the requested permissions. Further transparency methods include longitudinal behavioural profiling and multiple-source privacy analysis of app data access.
