The fastest way to check your Mac for malware

Open Activity Monitor (search for it in Spotlight by pressing Command+Space, type "Activity Monitor", then press Enter). Click the CPU tab. Look for programs you don't recognize using a lot of processing power — anything consistently above 50% when you're not actively using your computer is worth investigating. Write down the name of anything suspicious.

Next, restart your Mac in Safe Mode. Hold the power button until "Loading startup options" appears, click your startup disk, then click "Continue" while holding Shift. Your Mac will boot with only essential software running. If your computer runs noticeably faster or the suspicious program disappears from Activity Monitor, malware is likely present.

For a more thorough scan, download Malwarebytes for Mac (the free version is sufficient). Install it, open the program, click Scan, and let it run — this typically takes 10 to 20 minutes. Malwarebytes will flag anything it recognizes as malicious. If it finds threats, click Quarantine to isolate them.

Key Takeaways

  • Activity Monitor shows which programs are using the most processing power; anything consistently high when you're not actively using your Mac may indicate malware.
  • Restarting in Safe Mode disables most third-party software, so if your Mac runs faster or problems disappear, malware is a likely cause.
  • Malwarebytes for Mac (free version) scans your entire system and quarantines threats it finds without requiring payment to remove them.
  • Check your browser's homepage, search engine, and installed extensions — malware often hijacks these settings first.
  • Restart your Mac normally after scanning and removing threats to ensure all malicious processes are fully stopped.

Check your browser settings for hijacking

Malware frequently changes your browser's homepage, search engine, or adds unwanted extensions. Open your browser (Safari, Chrome, or Firefox) and look at what appears when you open a new tab. If it's not what you set, malware may have changed it.

In Safari, go to Preferences > General and check the Homepage field. In Chrome, go to Settings > On startup and look at what page loads. In Firefox, go to Home and verify your homepage setting. If any of these have been changed to something unfamiliar, change them back to what you want.

Then check your extensions. In Safari, go to Preferences > Extensions and remove anything you don't recognize. In Chrome, go to Settings > Extensions. In Firefox, go to Add-ons > Extensions. Malware often hides as a legitimate-sounding extension — look for anything with a vague name or that you don't remember installing.

Use your Mac's built-in malware protection

macOS includes XProtect, a system-level scanner that runs automatically in the background. You cannot access it directly, but it scans files you download and blocks known malware before it runs. XProtect updates regularly through your system updates, so keeping your Mac current is your first line of defense.

macOS also includes Gatekeeper, which verifies that programs you download come from trusted sources. When you open a downloaded app for the first time, Gatekeeper checks it against Apple's database. If you see a warning that an app is from an unidentified developer, that's Gatekeeper working — you can usually still open it by right-clicking and selecting Open, but this is a sign to be cautious.

To ensure XProtect and Gatekeeper are working, keep your Mac updated. Go to System Settings > General > Software Update and install any available updates. This is the single most important step you can take — most malware targets known vulnerabilities that updates patch.

What to do if you find malware

If Malwarebytes or Activity Monitor reveals malware, restart your Mac in Safe Mode again (hold power button, wait for startup options, hold Shift while clicking Continue). In Safe Mode, open Malwarebytes and run another scan. Safe Mode limits what malware can do, making removal more reliable.

After Malwarebytes quarantines threats, restart your Mac normally. Open Activity Monitor again and verify that the suspicious programs are gone. Check your browser settings a second time — if malware changed them, change them back again.

If the same malware reappears after removal, or if your Mac still runs slowly, the infection may be more serious. At that point, consider taking your Mac to an Apple Store or a local repair shop that specializes in Mac security. Some malware requires manual removal by someone with access to your system.

Prevent malware from infecting your Mac in the first place

Most malware reaches Macs through downloads, email attachments, or deceptive websites. Be skeptical of any file you download from an unfamiliar source. If a website asks you to download a "security update" or "player plugin" that you didn't search for, close the page — this is a common malware delivery method.

Email attachments are another common vector. If you receive an unexpected attachment from someone you know, contact them through another method (text, phone call) to confirm they sent it before opening it. Malware often spreads by compromising someone's email account and sending infected files to their contacts.

Use strong, unique passwords for your email and important accounts. If malware compromises one account, a strong password makes it harder for attackers to access others. Consider using a password manager like Bitwarden or 1Password to generate and store complex passwords.

When to seek professional help

If your Mac shows signs of malware but Malwarebytes doesn't find anything, or if problems persist after removal, professional help may be necessary. Some malware is sophisticated enough to hide from standard scanners, and some infections require manual removal.

Before taking your Mac to a repair shop, back up your important files to an external drive or cloud storage. This protects your data in case the repair process requires reinstalling your operating system. You can use Time Machine (System Settings > General > Time Machine) to back up automatically, or manually copy files to an external drive.

An Apple Store or certified Mac repair technician can run deeper diagnostics and remove stubborn malware. They may also check your Mac's hardware for damage, since some malware can affect system performance in ways that look like hardware problems.

Frequently Asked Questions

Can Macs get viruses?

Yes, though less commonly than Windows computers. Macs can get malware, ransomware, and spyware. The belief that Macs are immune is outdated — they're targeted less often simply because there are fewer Macs than Windows computers, not because they're technically invulnerable.

Is Malwarebytes enough, or do I need other antivirus software?

Malwarebytes plus macOS's built-in XProtect and Gatekeeper provide solid protection for most users. Additional antivirus software can slow your Mac and isn't necessary unless you frequently download files from untrusted sources or visit risky websites regularly.

What does "quarantine" mean in Malwarebytes?

Quarantine isolates a malicious file so it can't run or spread, but keeps it on your Mac so you can restore it if it was flagged by mistake. For most malware, you can safely delete quarantined files permanently — Malwarebytes will give you that option after scanning.

How often should I scan my Mac for malware?

If you're cautious about what you download and which websites you visit, scanning once a month is sufficient. If you download frequently from unfamiliar sources, scan weekly. If you notice your Mac running slowly or behaving strangely, scan immediately.

Will removing malware fix my slow Mac?

Often, yes — malware consumes processing power and storage space. However, if your Mac is still slow after malware removal, the slowness may be caused by a full hard drive, too many browser extensions, or aging hardware. Check your storage (System Settings > General > Storage) and close unnecessary browser tabs to see if that helps.