How to Detect Malicious Apps on Android and iPhone: 3 Steps to Check Yourself

SafePhone · Updated September 27, 2026

Your phone holds almost everything — photos, personal information, bank accounts, even passwords — which makes it a top target for hackers. The most common way to steal data from a phone is to trick you into installing a malicious app yourself. This guide shows you how to detect malicious apps on Android and iPhone in 3 steps: check the download source, check the permissions, and watch for unusual behavior after installing.

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Why malicious apps are the biggest threat on your phone

These days almost everyone has a smartphone, from children to grandparents, and many people spend more time on their phones than with friends and family. Because we keep everything on our phones, they've become a priority target for attack campaigns aimed at stealing personal information, business secrets or simply money.

Android and iOS have plenty of security mechanisms, but the weakest link is always the human. Most "I got hacked" incidents start with social engineering — psychological manipulation that gets users to hand over information, access or money themselves, rather than attacking the device directly. On phones, in the vast majority of cases, scammers need to trick you into installing a malicious app yourself; once installed, it quietly steals your data and sends it back to them. So if you know how to spot malicious apps, you've already blocked most of the risk.

The rest comes from attacks exploiting zero-day vulnerabilities — much rarer and requiring genuine hacking skills, covered briefly in Step 3. Learn more about the different kinds of malware in types of malware and see the bigger picture in common online threats.

Step 1: Check where the app comes from

The golden rule: only download apps from the two official stores that come preinstalled on your phone — Google Play (Android phones such as Samsung, Pixel, Xiaomi, Oppo…) and the App Store (iPhone). Never install apps from anywhere else, whatever the reason, however urgent it sounds, and whoever is asking.

APK files on Android: the clearest sign of a scam

Android apps are packaged as .apk files and signed with the developer's digital signature. Apps on Google Play are also tied to a registered developer account, so users can see who's behind the app. You can view the developer's details (name, email, address, website) under App support on the app's store page.

APK files can also be installed directly: you tap the file in your Downloads folder, and Android shows a warning and asks for permission to install apps from unknown sources. This is really meant for developers testing their apps. For ordinary users, being walked through installing an APK file yourself is a clear sign of a malicious app. If anyone asks you to do this, don't trust them, and report it to the police.

A typical APK scam goes like this:

1. You see a Facebook post: install this app to get a free $1,000 for early users.
2. You tap the download link and your phone saves the APK file to your Downloads folder.
3. You follow the "installation guide" next to it: open Settings, turn on "install unknown apps", then tap the APK file.
4. Android warns you that the APK comes from an unknown source, but the guide tells you to just tap Accept.
5. The malicious app is installed and starts stealing your data.

Fake iPhone apps via TestFlight

iOS apps are packaged as .ipa files and can normally only be installed through the App Store or developer tools like Xcode. However, scammers can abuse TestFlight — Apple's official tool for distributing beta versions before they're released on the App Store. TestFlight is legitimate, but it can be exploited in scams:

1. A scammer poses as a bank employee or police officer, calls you, knows your name and address, and threatens you: "Your account received money from a criminal gang", "The police are investigating you for money laundering". They send you a link to install an "internal app" so you can "prove your innocence".
2. You tap the link, and your iPhone opens the App Store to install TestFlight if you don't already have it.
3. You're asked to tap the link again — this time the fake app is installed through TestFlight.
4. The fake app looks exactly like the real banking app, so you don't suspect anything.
5. The app steals your data or tricks you into entering your username, password, OTP and even your card's CVV.

Step 2: Check the permissions the app requests

Once users become wary of unknown download sources, scammers switch to a second trick: hiding in plain sight on the official stores.

1. They write or buy the source code of an ordinary app and publish it on Google Play or the App Store.
2. Because the app is harmless, the store approves it for download.
3. Later updates add "new features" that require system permissions: reading contacts, call logs, the photo library, GPS location…
4. They advertise the app's "amazing" features, aimed squarely at the needs of a specific group of users.
5. Curious users install it from the official store.
6. The app requests lots of permissions; users don't notice or don't understand, so they tap Allow on everything.
7. Using those very permissions, the app pulls call logs, photos, location and more from the phone.

Android and iOS both protect sensitive data with a permission system: developers must declare permissions (for example "access photos"), and when the app needs them, the operating system shows a dialog asking you. Only if you agree can the app read that data. That's why checking permissions is an effective way to spot malicious apps. The menu names below may vary by OS version and phone manufacturer.

How to check app permissions on Android

Before tapping Install:

1. Open the app's page on Google Play.
2. Open About this app → scroll down to App permissions → See more.
3. See what the app can access: location, contacts, storage, microphone, SMS…
4. Also read the Data safety section to see what data the app collects and shares.

After installing:

1. Go to Settings → Privacy → Permission manager.
2. Choose a permission, such as Location, to see which apps are using it.
3. Set the right level: Allow all the time, Allow only while using the app, or Don't allow.

Tip: Android asks for permission the first time an app needs it — don't always tap "Allow"; prefer "Allow only while using the app".

How to check app permissions on iPhone (iOS)

Before tapping Get:

1. Open the app's page on the App Store.
2. Scroll to the App Privacy section.
3. See what data the app may collect: location, contacts, identifiers, usage data…

After installing:

1. Go to Settings → Privacy & Security.
2. Choose a category such as Location Services, Photos or Microphone.
3. Pick the app and its access level: Never, Ask Next Time, While Using the App or Always.

Which permissions are suspicious?

Ask yourself: which feature of this app actually needs this permission? If the permissions go far beyond the features, that's a warning sign.

Be especially careful with the Accessibility permission and device admin permission: they let an app read your screen, tap on your behalf and resist being uninstalled — and fake banking apps often abuse them. To understand why a security app needs certain permissions, see call screening permissions on Android and iOS.

Step 3: Watch your phone's performance after installing an app

Thanks to the App Store and Google Play review processes, most malicious apps get removed — but don't be too optimistic. At the highest level are zero-day exploits: vulnerabilities that haven't been disclosed, not even among experts, and have no patch yet.

Android and iOS are software too, so they can have bugs and vulnerabilities. These flaws are hunted aggressively; some are sold for high prices or used as weapons by certain governments, and in the hands of attackers they become a way into your phone. Although rare for ordinary users, after installing a new app you should still watch for:

• Is the device slower than before?
• Does it suddenly run hotter or drain its battery faster?
• Is it stuttering or lagging unusually?
• Any other odd behavior: apps opening on their own, mobile data usage spiking, ads popping up outside the browser?

Many exploits put a heavy load on the device while running, so they can make your phone slow, hot or laggy. These signs don't prove your phone has been attacked, but they're a good reason to uninstall the app you just added and check carefully. The best defense against zero-days is to update your operating system as soon as a patch is available.

Checklist before you tap "Install"

• Is the app on Google Play or the App Store? Not an APK file, and not a TestFlight link from a stranger.
• Does the developer name match the brand (bank, government agency)?
• Do the download count, release date and reviews make sense? Be careful with brand-new apps packed with near-identical 5-star reviews.
• Are the requested permissions proportionate to the features?
• Who recommended the app to you? A caller, a strange text message or a "free gift" ad are all red flags — see how scam ads target you.
• Does the download link lead to the official website? If you're not sure, paste it into SafePhone to check if the website is a scam.

What to do if you installed a malicious app

1. Turn on airplane mode to cut off the app's connection.
2. If you entered banking details, immediately call your bank's official hotline to lock your account and cards.
3. Revoke the app's Accessibility and device admin permissions (if any), then uninstall it. On iPhone, delete the app and check Settings → General → VPN & Device Management for any unfamiliar profiles.
4. Run a scan with Google Play Protect (Android).
5. Change your email, social media and banking passwords from another device and turn on two-factor authentication.
6. Tell your family and friends so they watch out for messages impersonating you, and report it to the police if you've lost money.

Conclusion

Most phone data theft needs you to install the app yourself. With just three habits — download only from official stores, scrutinize permissions, and watch performance after installing — you can detect malicious apps before they do any harm. Share these steps with your parents and young children, the people most easily lured into installing apps.

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