How to Scan Your PC for Malware With the Free Malwarebytes Scanner

Your PC feels haunted: pop-ups appear from nowhere, your browser homepage changed itself, programs you never installed show up, or everything suddenly runs like it is wading through mud. These are classic malware symptoms — and the best free tool for hunting the infection down is the Malwarebytes free scanner, the program technicians reach for first.

This guide shows you how to download Malwarebytes safely, run a proper scan, deal with what it finds, and tidy up afterwards so the infection does not simply return.

Quick Answer

To scan your PC with the free Malwarebytes scanner: download Malwarebytes from malwarebytes.com, install it (you can decline or later ignore the Premium trial), click “Scan” on the main screen, and let it check memory, startup items, the registry and the file system. When it finishes, review the detected items and click “Quarantine” to neutralise them, then restart your PC if asked. The free version scans and removes malware on demand but does not include always-on real-time protection — your regular antivirus (such as Microsoft Defender) stays your full-time guard.

Why Malwarebytes Finds Things Your Antivirus Missed

Malwarebytes specialises in the grey zone of modern threats: adware that hijacks browsers, potentially unwanted programs (PUPs) bundled with downloads, rogue “driver updaters,” browser redirectors and the leftover traces of bigger infections. Traditional antivirus focuses on classic viruses and known malware files, so the two tools genuinely complement each other. Running a Malwarebytes scan is called a “second-opinion scan,” and it is standard practice even on PCs with good antivirus installed. It is not a sign your antivirus failed — it is how thorough cleaning works.

Step 1: Download and Install Malwarebytes Safely

1. Go to the official site. Type malwarebytes.com into your browser yourself — never click a “Malwarebytes download” ad or a link from a pop-up, because fake versions exist.
2. Click “Free Download” and save the installer (MBSetup).
3. Run the installer. Choose “Personal Computer” when asked, and pick your language and install location.
4. Decline extras politely. The installer may offer the Malwarebytes Browser Guard extension and start a 14-day Premium trial automatically. Both are optional; the trial simply reverts to the free scanner when it ends, with no charge and no card details taken.
5. Let it update. On first launch Malwarebytes downloads the latest threat database. This matters — an out-of-date scanner misses new threats.

Step 2: Run a Full, Proper Scan

1. Close your browsers and save your work. The scan is quick, but quarantine and restart steps go more smoothly with everything closed.
2. Click the big “Scan” button on the main screen.
3. Wait while it works through its stages: checking for updates, scanning memory, startup items and registry, then the file system. A typical PC scans in 5–20 minutes.
4. Review the results screen. Malwarebytes lists everything it found — malware, PUPs and PUMs (potentially unwanted modifications) — with tick boxes. Items are pre-ticked sensibly; unless you are an expert who recognises a false positive, leave the ticks exactly as they are.
5. Click “Quarantine.” The selected threats are disabled and moved to a sealed quarantine area where they cannot run.
6. Restart if prompted. Some infections can only be fully removed during a reboot — do not skip this step.

After the restart, open Malwarebytes again and run a second scan. A clean second result (zero detections) is your confirmation the infection is gone. If the same items keep returning, the infection may have a persistent component — note what is found and consider a scan with Windows Defender Offline, which runs before Windows loads.

What Quarantine Means (And How to Undo It)

Quarantined items are not deleted outright; they are encrypted and parked in a holding area inside Malwarebytes (Detection History > Quarantined items). If a legitimate program stops working after a scan — rare, but possible — you can restore its file from quarantine from that screen. Leave everything else quarantined for a week or two of normal use, then delete the quarantined items permanently once you are sure nothing is missed.

Keeping the Infection From Coming Back

Removing malware treats the symptom; these steps treat the cause. Update Windows and your browser. Uninstall the program whose download bundled the junk — free download sites and “cracked” software are the top sources. Turn Microsoft Defender’s real-time protection back on if anything disabled it (check in Windows Security > Virus & threat protection). And read our explainer on the difference between antivirus and anti-malware tools to build a layered defence that suits your PC.

Common Mistakes and Pro Tips

• Mistake: downloading Malwarebytes from a sponsored ad. Fake security downloads are a real infection vector. Type the official address yourself.
• Mistake: stopping after one scan. Always rescan after the restart. The second clean scan is the proof, not a formality.
• Mistake: unticking detections because there are “too many.” A long list is normal with adware bundles — they install in packs. Quarantine everything it flags.
• Tip: scan in tough cases with rootkit scanning on. In Settings > Security, enable “Scan for rootkits” if ordinary scans keep finding the same returning infection.
• Tip: schedule a monthly free scan. The free version does not scan automatically, so put a monthly reminder in your calendar — five minutes keeps small problems small.

Signs Your PC Might Be Infected (When to Run This Scan)

Not sure whether your PC’s odd behaviour justifies a scan? Run one anyway — it is free and takes minutes — but these are the classic symptoms that should send you straight here: browser pop-ups appearing when no browser is open; your homepage or search engine changing without your involvement; new toolbars, extensions or programs you do not remember installing; a sudden, permanent slowdown with the fan roaring at idle; your antivirus reporting that it has been disabled; friends receiving strange messages from your accounts; and Windows warning icons turning yellow or red in the taskbar. One symptom alone can have an innocent explanation — an aging hard drive slows down all by itself — but two or more together deserve a Malwarebytes scan the same day. The earlier an infection is caught, the less it can steal, encrypt or break, and the simpler the cleanup tends to be.

Conclusion

When your PC misbehaves, the free Malwarebytes scanner is the fastest reliable answer: download it from the official site, run a full scan, quarantine everything it finds, restart, and scan once more to confirm zero detections. Then fix the habit that let the infection in — safer downloads and updated software — and your PC should stay clean.

Frequently Asked Questions

Is the Malwarebytes free scanner really free?

Yes. The free version scans for and removes malware, adware and unwanted programs at no cost, forever. It starts with a Premium trial that expires automatically — no payment details are taken, and the scanner keeps working afterwards.

Does Malwarebytes replace my antivirus?

The free version does not provide real-time, always-on protection, so it does not replace your antivirus. Keep Microsoft Defender (or your chosen antivirus) active as your full-time guard, and use Malwarebytes free as a regular second-opinion scanner.

How long does a Malwarebytes scan take?

A standard threat scan usually takes 5–20 minutes depending on your PC’s speed and how many files you have. The first scan after installation, and scans with rootkit detection enabled, take longer.

What should I do if Malwarebytes keeps finding the same threat?

Restart and scan again first — some items only clear on reboot. If it persists, enable rootkit scanning in settings and run a Windows Defender Offline scan, which operates before Windows starts and can remove stubborn, deeply hooked infections.

Can Malwarebytes remove viruses as well as adware?

Yes. Although it is famous for adware and unwanted programs, the scanner detects and removes viruses, trojans, ransomware traces, spyware and rootkits too. It is a full malware scanner, not just an adware cleaner.