Google Play App Security: Update Risks

TL;DR

Yes, attackers or law enforcement could compromise apps in Google Play and deliver a malicious update to your device. However, Google has several layers of security to make this difficult. You can significantly reduce the risk by being cautious about app permissions, checking developer reputation, using Google Play Protect, keeping your device updated, and considering alternative app stores or sideloading with extreme care.

Understanding the Risks

An attacker gaining control of a legitimate app’s developer account is the primary way this happens. They could then push a malicious update disguised as a normal version. Law enforcement might also request such access under legal warrants, though this is less common and usually involves specific targets.

How Google Protects You

1. Google Play Protect: This scans apps before you download them and periodically checks your installed apps for malicious behaviour. It’s enabled by default on most Android devices.
2. App Signing: Developers use digital signatures to verify the authenticity of their apps. Google checks these signatures when an update is released. If the signature doesn’t match, the update should be blocked (though vulnerabilities exist – see below).
3. Review Process: Google reviews apps submitted to Play Store, though this isn’t a perfect system and malicious apps can sometimes slip through.

Steps to Protect Yourself

1. Check App Permissions Carefully: Before installing any app (especially updates), review the permissions it requests. Does a flashlight app really need access to your contacts? Be suspicious of excessive or irrelevant permissions.
   • Go to Settings > Apps > [App Name] > Permissions on your Android device.
2. Research the Developer: Look at other apps by the same developer. Do they have a good reputation? Are there any reports of malicious behaviour associated with their apps?
   • Check the developer’s website (if available).
   • Search online for “[Developer Name] security issues”.
3. Keep Your Device Updated: Android updates include important security patches that protect against vulnerabilities. Install them as soon as they become available.
   • Go to Settings > System > System update on your Android device.
4. Enable Google Play Protect: Make sure it’s turned on.
   • Open the Google Play Store app.
   • Tap your profile icon in the top right corner.
   • Select Play Protect and ensure it’s enabled.
5. Be Cautious with Sideloading: Installing apps from sources other than Google Play Store (sideloading) is much riskier. Only do this if you absolutely trust the source.
   • If sideloading, verify the app’s checksum against a trusted source before installation.
6. Consider Alternative App Stores: Some alternative app stores (like F-Droid for open-source apps) have stricter security policies.

What if an Update is Compromised?

1. Look for Unusual Behaviour: If your device starts behaving strangely after an update (e.g., unexpected ads, battery drain, data usage), it could be a sign of malware.
2. Uninstall the App: Immediately uninstall the app if you suspect it’s compromised.
   • Go to Settings > Apps > [App Name] > Uninstall on your Android device.
3. Run a Malware Scan: Use a reputable mobile security app to scan your device for malware.
4. Factory Reset (Last Resort): If you’re unable to remove the malware, a factory reset may be necessary. Back up your important data first!

Technical Considerations

While app signing is a strong security measure, vulnerabilities have been discovered that allow attackers to bypass it in certain circumstances (e.g., compromised build systems). Google continuously works to address these issues.