Does Factory Reset Remove Viruses? Fixing Smartphone Malware

There are over 7 billion smartphones in use worldwide. Protecting them from viruses, spyware, and other malware is more important than ever. A common solution that many people resort to when dealing with infected devices is a factory reset. But, does a factory reset remove viruses from smartphones?

Generally, a factory reset will remove viruses on smartphones. Mobile operating systems use an app on its recovery partition during a hard reset to restore factory settings. Malicious apps on mobile devices are less prevalent than on desktop systems where antivirus software is crucial.

First of all, what is a factory reset? Is it effective? Here is what I know:

Man touching a virus with one hand while doing a factory reset to remove the virus in the other

Effectiveness of a Factory Reset in Removing Malware

Smartphones store their information on their internal flash memory. This information includes contacts, images, apps, movies, files, settings, and other data.

There is malware that hides in the device’s memory. Examples include malware downloaded as a standalone file. Or, viruses and spyware that have infiltrated the device’s operating system or apps.

What happens when you perform a factory reset? You remove all data from the device’s storage, including malware that has infected it.

A factory reset is a process that restores a device to its original factory settings. It sanitizes the device. It erases all data and software installed after the device was first purchased.

A key takeaway is that a factory reset removes only viruses that are present on the device’s storage.

So, beware that a factory reset is ineffective in removing certain viruses. What types of viruses are those?

Exception: Some Factory Resets Do Not Remove Viruses

A factory reset does not clear some types of viruses.

A factory reset can not remove a virus that has gotten onto the phone’s system files or recovery partition using elevated privileges.

The good news is that this type of malware is very rare. This type of rootkit attack often gets into the phone when you root or jailbreak a device.

The only viable way to counter this advanced type of malware is to flash the hardware or dispose of the cell phone. Hopefully, your smartphone wasn’t too expensive.

A virus can also survive a factory reset if it has replicated itself to backups or other devices connected to the same network. In this case, even after a factory reset on your device, it will be re-infected. Thus, also check and clean connected devices to prevent re-infection.

Now that we’ve covered the effectiveness of a factory reset, below are telltale signs of a smartphone that possibly needs a factory reset.

My Smartphone is Slow. Does It Have A Virus?

If your Android smartphone or iPhone has recently become sluggish, a few possible causes aren’t necessarily the result of a virus or malware infection. Here are a few common examples:

  • Outdated hardware
  • Poor internet connection
  • Too many open or installed apps
  • Insufficient storage space on the device
  • Older or unpatched mobile operating system

Note: It’s common for phone models to become slow over time. Not because of the device’s hardware components but because of the storage and performance demands of newer software programs and operating system upgrades downloaded on your phone. Because those updates are usually designed for newer phone models, older devices might not manage them as well.

Try these four techniques to speed up a sluggish Android phone:

  • Clear the cache
  • Disable live wallpapers
  • Check for app updates and patches
  • Uninstall unused or infrequently-used apps
  • Back up files and photos, secure cloud storage, and clear the phone’s memory
  • Restart your cell phone

If none of the above works and your phone continues to lag, you may need to perform a factory data reset as a last resort for your iPhone or Android device.

Remember:A factory data reset will delete all data from the phone, including viruses, returning it to its original software settings.

If, after a factory reset, your device is still not operating at acceptable performance levels, then it may be time to look at other options.

Man on a park bench with two smartphones wondering if a factory reset will protect against hackers

Benefits Of A Factory Reset on Smartphones

The benefits of a factory or hard reset are:

  • Removal of viruses or malware
  • Fewer apps to manage and keep updated
  • More privacy with fewer apps synchronizing data
  • Longer battery life with fewer apps using the internet
  • Improved smartphone performance
  • Free up storage space on your device by clearing junk files
  • Securely wipes old data with full phone encryption enabled
  • Correcting any mistaken OS or app settings
  • Resets permissions for better privacy
Important:Continuing risky use of your Android smartphone or iOS device will still put you at risk of being hacked again. Manufacturers have put safeguards in place to prevent hacks. Lean on these best practices.
Man on a train using his smartphone now using good habits after he performed a factory reset

Safety Tips To Prevent Getting a Virus Again After a Factory Reset

After you’ve gone through the effort of re-installing all your apps and data to your Android smartphone, you’ll also want to reset your personal usage habits to prevent future needs to hard reset.

1. Do a weekly (hard) reboot

These smartphones are fantastic at not requiring frequent resets. I’ve gone weeks or months without power cycling my phone. But, the excellent Techlore YouTube channel reported on an excellent idea: Reboot your smart device every week.

Here’s the video (I’ve scrubbed it to the point)

While they’re referring to mitigating an issue on Apple iOS devices using a force reboot, the advice holds by clearing in-memory attacks. There’s no downside from what I can tell, though; I might execute a standard, soft reboot.

2. Only (re)install apps you need

Apps continuously collect usage data and report home. They are also a maintenance source, as bug fixes must be regularly installed or patched. The more apps you download, the more opportunities for your phone to become vulnerable.

Avoid installing apps you don’t intend to use more than a few times. You can often use the mobile web version of many services instead of the iOS or Android app.

Don’t forget apps also use your phone’s memory and persistent storage while edging you towards any data caps or internet usage quotas.

3. Only install apps from the official app store

Only use the official app store when you re-install apps after a factory reset. Apps downloaded through other channels have a higher chance of, in fact, being malicious.

Simple as that.

There’s one exception to getting apps from places other than the Google Play Store that I consider acceptable and even desirable.

4. Advanced Android users should stick with F-Droid

F-Droid is a collection of free and open-source software (FOSS) apps for the Android platform. There are no monitoring or hidden fees in any of the apps in the library.

This unofficial app store contains software developed by a community of volunteer developers. Since the source code is readily available, coders can audit the programming to discover suspicious activity.

F-Droid has meticulously documented its external security audits and has a history of correcting issues.

Any apps with potentially non-compliant, undesirable features, or even promoting non-free data are clearly identified. This flagging gives users transparency and the ability to decide if they want to download and install the app.

5. Never sideload apps from untrusted sources

I want to stress the importance of not downloading and installing apps from untrusted sources.

Users frequently ask if it’s ok to get unlocked versions of premium apps from various websites. The answer is an unequivocal no. Sites offering hacked versions of paid apps can inject malware.

Think About It: You’re willingly installing a pre-hacked app to your smartphone, which you use daily and contains all your sensitive data with a live internet connection. Dangerous.


Does A Factory Reset Stop Hackers?

A hard or factory reset is the best way to un-hack any tablet or phone and counter future attacks.

The reset function in most Android phones essentially wipes the whole device, returning it to its original state and hence the name “factory reset.” It eliminates all data, history, contacts, apps, photos, downloads, customized settings, and other user data.

Fortunately, it will also remove all types of malware, including viruses, spyware, ransomware, infected downloads, and other malicious software.

The downside is that all your applications and data will be wiped out. If you’ve been backing up your device, re-installing your apps and restoring data should be somewhat straightforward, albeit time-consuming.

I like calling a factory reset the nuclear option ☢️ because it works for all phones, including iOS devices, and levels the device to a ground state.

This approach will give you peace of mind even in scenarios where you’re unsure if your phone is hacked.

Mike Chu

Mike is a web developer and content writer living as a digital nomad. With more than 20 years of devops experience, he brings his "programmer with people skills" approach to help explain technology to the average user. Check out his full author bio by clicking here.

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