In brief
Before downloading an app, understand its permissions and weigh the risk of personal data theft. This 2015 article explains how background threads can drain batteries, why unnecessary permissions raise concerns, and how Google and Apple's review procedures differ.
When you turn on your phone, which app do you use first? Facebook? Whatsapp? Or do you check your email? Generally, we visit the App Store or Google Play to download the apps we want and do what we need to do. Over time, you may notice that even a fully charged phone quickly runs out of battery while idle. There have also been numerous reports of phones being monitored or infected with malware, and many online tutorials advise owners to format their phones and back up their data. With this in mind, I would like to share some insights from the perspectives of programming and users.
1. Turning off your phone does not necessarily stop all activity: you never know what programs apps are running in the background
In computing, a program running in the background is called a thread. A thread runs independently in the background, separately from the main program. By implementing a callback method in the background, the home page can be updated periodically. In Android / iOS, there are three types of threads: those that run a single task, those that repeat a task, and those that continuously use a backend class.
All of these threads can quickly drain your phone's battery unless you stop them through the settings or bring up the app stack and swipe them away. Even when you exit an app using the normal steps, its threads may not stop running.
If you have experience developing Android apps, you will understand that all startup and shutdown procedures are initially triggered by capturing button events. Even after you leave an app, a thread created by its developer requires you to stop it through the settings.
Hackers can intercept the events triggered by pressing and releasing the button during shutdown, and run a thread to do anything. If you have rooted your phone or jailbroken your iPhone, apps can even steal all your user data, along with the email addresses and phone numbers in your contact list.
2. Apps that request too many unnecessary permissions raise security concerns
Many app developers, particularly those focused on Android development, enable a few extra permissions to make improvements easier. This is particularly common with camera and flashlight apps:
If you pay a little attention, you will realise that turning on the flashlight has nothing to do with enabling Wi-Fi or accessing user data. Yet users in a hurry often overlook which permissions an app requests on their phone. Google and Apple also take very different approaches to approving apps for publication. Google scans the APK only once to check for obvious Trojans and whether the content meets its requirements; an app can be published in as little as two hours. Apple, however, takes several weeks. Once screenshots and text descriptions have been submitted, the entire review is conducted manually. If an app needs to communicate or work with other electronic devices, Apple app reviewers will also ask the developer to submit a demonstration video so that others can understand how to use the app. As a result, people are generally more likely to believe that iOS apps are safer than Android apps.
As we can see, apps are convenient but carry hidden risks. Before downloading an app, pause and consider whether you clearly understand the permissions it uses and have weighed the risk of your personal data being stolen. Whether storing data in the cloud is safe is a topic we will leave for another opportunity.