How to check your PC for malware
If your computer feels off — running slowly or showing odd background processes — several built-in and third-party tools can help confirm whether malware is present. Experts recommend combining scans for a fuller picture.
Today's malware often works quietly in the background, aiming to harvest sensitive data without drawing attention, unlike the obvious pop-up-filled infections of the past. Still, warning signs can include a PC suddenly slowing down, freezing more often, or unfamiliar processes running.
Built-in protection
Windows 11 includes Microsoft Defender as part of the Windows Security suite, and it scans automatically by default. Its "Virus & threat protection" section lets users review allowed threats and protection history. A quick scan checks only the most common infection spots, while a full scan examines the entire system and takes longer. For deeper checks, an offline scan restarts the PC into the Windows Recovery Environment, where hidden threats are easier to catch. It's also worth confirming the firewall is enabled for all connection types.
Additional scanning tools
For a second opinion, standalone scanners like Malwarebytes offer on-demand quick, custom, or deep scans in their free version, with options to quarantine or remove anything found. Malwarebytes also offers a separate free tool, AdwCleaner, aimed specifically at adware. For more advanced troubleshooting, running scans in safe mode without a network connection can help, as can Microsoft's monthly Malicious Software Removal Tool or third-party options such as ESET Online Scanner, Emsisoft Emergency Kit, and VirusTotal.
Paid third-party antivirus subscriptions are generally unnecessary, since they frequently push upgrade prompts, while Microsoft has strong incentive to keep Defender effective on its own.
Prevention still matters most
If scans from multiple tools come back clean, the PC is likely free of malware. However, no antivirus tool can fully protect against weak passwords, phishing sites, or phone scams — making cautious everyday habits the most reliable defense against threats overall.
