How a Factory Reset Works

A factory reset (also called a hard reset or master reset) essentially wipes your device clean, erasing all user-installed software, files, and settings, then restoring the operating system to the default version provided by the manufacturer. On a smartphone or tablet, this means removing data like photos, messages, downloaded apps, accounts, and customized settings. On a computer, this can also remove installed programs, user accounts, and system modifications. Theoretically, because most malware and viruses reside in user data or installed applications, wiping them out should also remove the malware that came with them.

Most standard viruses, malware, and unwanted programs rely on files stored in the user environment or system folders that a reset removes. By returning the device to a clean baseline, these threats are typically eliminated because their execution files are no longer present. However, like all cybersecurity practices, there are caveats and limitations to this approach that every user should understand before relying solely on a reset as a fix.

When a Factory Reset Successfully Removes Malware

In the vast majority of cases, a factory reset *will remove* viruses or malware because the reset deletes everything on the device that was installed after purchase. This includes:

Malicious apps disguised as legitimate software – Malware installed through downloads from unverified sources or phishing links is wiped when the device is restored to default settings.
Spyware and adware – Programs designed to spy on you or display unwanted ads are removed along with all user data and installed apps.
Trojans and standard malware – These threats typically live in application directories or user files that the reset eliminates.

By completely erasing and rebuilding the operating system to its original state, the reset breaks the persistence of most conventional malware infections. This is why security experts often recommend a factory reset as a last-resort measure when all other malware removal steps fail.

Scenarios Where a Factory Reset Might Not Remove a Virus

Although a factory reset is effective against most malware, some threats can survive this process under certain conditions. These include:

Firmware-level malware – Some advanced malware can infect the low-level firmware of a device. Because a reset typically refreshes only the operating system and user storage, firmware infections remain intact and can reinfect the OS after reboot.
Rootkits and bootkits – These sophisticated threats embed themselves deeply within a system, sometimes affecting the boot sector or operating system loader. Because they operate below the level most resets target, they can persist even after a reset.
Infected backup restores – If you use a backup containing malware to restore your data after a factory reset, you may inadvertently reinstall the same threats you were trying to remove.
Compromised recovery partitions – Some devices store restore data in a recovery partition. If this recovery environment has been compromised, the reset may restore an infected version of the system.

While these scenarios are relatively rare, they highlight that a factory reset is not a universal guarantee against every type of malware threat, especially those designed to evade detection and removal.

Signs That Malware Might Still Be Present After a Reset

After a factory reset, your device should perform like new. However, there are signs that could indicate a lingering infection:

Reappearance of unusual behavior – Strange pop-ups, unexpected reboots, or unsolicited app installations can indicate an issue.
High data usage or resource consumption – Malware often runs background processes that use data or CPU cycles.
Unexpected network traffic – If your device connects to servers you don’t recognize, it may still be compromised.
Unauthorised account access – If your accounts continue to be accessed from unknown locations, you may need to secure those accounts separately.

In such cases, it’s important to verify whether the symptoms are caused by malware or simply misconfigured apps and settings.

How to Ensure Your Device Is Truly Clean

To maximize the chances that your device is clean after a reset and reduce the risk of reinfection:

Use trusted antivirus tools beforehand – Scanning your device with reputable security software can identify and remove threats before you reset, and help ensure backups are clean.
Backup carefully – Only restore data that you are confident was created before the infection occurred, and avoid restoring apps that could contain threats.
Update your system immediately – After a reset, install all pending system and security updates to protect against known vulnerabilities.
Install apps only from official sources – Whether on mobile or desktop, avoid third-party app stores and unverified downloads.
Change passwords and enable two-factor authentication – This secures accounts that might have been compromised before the reset.

Good security practices significantly reduce the chance of reinfection and improve your long-term digital safety.

Alternative Methods to Remove Malware Without a Factory Reset

If you’re hesitant to perform a factory reset because of data loss, there are alternatives that can sometimes remove malware without wiping everything:

Safe Mode scans – Restarting your device in safe mode can prevent malware from running and make it easier to uninstall suspicious apps.
Third-party malware removal tools – Reputable antivirus or anti-malware programs can scan for and remove threats while preserving your data.
Manual removal of suspicious apps – If you can identify the malware file or app, uninstalling it manually may resolve the issue without a reset.
Firmware re-flashing for advanced cases – For persistent infections, especially on Android devices, reflashing the stock firmware will completely overwrite all software and often removes even deeply rooted threats.

These methods may be less disruptive than a full reset but require careful attention and sometimes technical knowledge.

Preventing Malware Infections in the Future

Prevention is always better than cure when it comes to cybersecurity. To avoid future infections:

Keep devices updated – Regularly install operating system and application updates to patch known security holes.
Avoid suspicious links and attachments – Phishing links are a common way malware spreads, so exercise caution in emails and messages.
Use security tools – Antivirus, anti-malware, and network protection apps or software help catch threats early.
Practice safe browsing – Stay away from untrustworthy sites and use browsers with built-in security protections.
Educate yourself and others – Awareness of common malware tactics reduces the likelihood of infection.

These best practices protect your devices and personal data over the long term and complement the effectiveness of tools like resets and scans.

Conclusion

A factory reset can be a powerful tool for removing viruses, malware, and unwanted software, but it is not infallible. In most common cases, especially for user-level malware that infects apps and files, a reset will eliminate the threat. However, sophisticated threats that target firmware, boot sectors, or recovery partitions can survive this process. To effectively secure your device, combine a reset with careful pre- and post-reset checks, trusted security tools, and preventative practices. By understanding both the strengths and limitations of factory resets, you’ll be better equipped to keep your devices safe and running smoothly into 2026 and beyond.