Start with Windows Security: run a Quick scan, then a Full scan if concern remains. If you still suspect a remote access trojan (RAT), run Microsoft Defender Offline and review Protection history when Windows restarts. A clean scan is useful evidence, but it does not prove that a PC is free of unauthorized access.
Run the built-in Windows Security scans
Windows Security provides a practical first check for malware. Scan names and availability can vary with Windows version, security-provider configuration, and organizational policy.
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- Run a Quick scan. Open Windows Security > Virus & threat protection, then select Quick scan. Microsoft recommends starting a scan when you suspect malware. Microsoft’s Windows Security scan guidance.
- Run a Full scan if concern remains. On the same page, select Scan options, choose Full scan, and start it. This is a deeper scan that runs in Windows; allow it time to finish.
- Use Microsoft Defender Offline for a deeper check. In Scan options, choose Microsoft Defender Offline scan and start the scan. Save open work first: the PC restarts and scans outside the usual Windows session, which can make it harder for persistent malware to hide. Microsoft’s instructions are at Microsoft Defender Offline support.
- Check the result. After the PC returns to Windows, open Windows Security > Virus & threat protection > Protection history to review detections and actions.
Offline scanning has prerequisites: Microsoft documents an enabled Windows Recovery Environment and appropriate Defender configuration. If BitLocker is enabled, Windows may ask for the recovery key after the restart. See Microsoft Defender Offline in Microsoft Learn for technical details and supported-platform information.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsUnderstand what scan results can and cannot tell you
| Scan | What it offers | Disruption |
|---|---|---|
| Quick scan | Initial check recommended when malware is suspected. Microsoft | Runs in Windows; no restart stated in Microsoft’s consumer scan guidance. |
| Full scan | Deeper in-Windows scan option. Microsoft | Runs in Windows; allow it to finish. |
| Microsoft Defender Offline | Scans outside the normal Windows session. Microsoft | Restarts the PC; BitLocker may require a recovery key, and technical prerequisites apply. Microsoft Learn |
A detection is evidence to investigate and act on; follow the action Windows Security reports and review Protection history. Conversely, a clean result does not establish that no RAT or unauthorized access is present. The cited consumer guidance does not describe any scan as a guarantee against every compromise.
#1 Best Overall
- POWERFUL SECURITY KEY: The Security Key C NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
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Recognize warning signs without treating them as a diagnosis
Possible malware clues include a suddenly slow PC, reduced battery life, increased data use, unexpected pop-ups or ads, browser redirects, crashes, unresponsive behavior, blocked security sites, or an unexpected browser-homepage change. These symptoms are not specific to RATs. Microsoft cautions that the same problems can arise from hardware or software issues unrelated to malware. See Microsoft’s malware and virus removal guidance.
A RAT can give an attacker remote control and may be used to record keystrokes or browsing activity or send information such as passwords and browsing history. Trojans can masquerade as legitimate applications, and Microsoft notes that they may use the same file names as real apps. Those capabilities explain why a familiar-looking name or unusual behavior alone cannot confirm an infection. Microsoft’s Trojan malware overview.
Rank #2
- POWERFUL SECURITY KEY: The Security Key NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key NFC via USB-A and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
Check remote-access software carefully
Remote-access tools have legitimate uses, including technical support and administration, but attackers can misuse them too. Finding such a program on its own does not prove compromise. Before removing anything, establish whether you, your employer, or a support provider installed it and whether its use is authorized.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →For organizations, CISA recommends inventorying authorized remote-access tools and investigating abnormal execution, such as a remote-management program running as a portable executable. Legitimate tools may blend into normal activity and may not trigger antivirus or endpoint defenses. See CISA’s Guide to Securing Remote Access Software and its Ransomware Guide. These are organizational security resources, not a consumer checklist for identifying a RAT from an app name alone.
Quick Recap
Best Value
- Ultra-Compact FIDO2 Security Key - Plug-and-stay or carry on a keychain. This USB-A hardware security key offers portable, always-on protection for desktop and mobile use. (Item Size: 0.75 X 0.74 IN x 0.25 IN)
- USB-A Hardware Key for All Devices - Works with USB-A ports on PC, Mac, Android, and other laptop/notebook device. Enables secure, cross-platform login with FIDO2.0 passkey support.
- FIDO Certified Security Key - Meets FIDO and FIDO2 standards. Works with Google, Microsoft, GitHub, Dropbox, and more. Please check service compatibility before purchase.
- Passwordless Login with Passkey - Supports passkey login via WebAuthn and CTAP2. Enjoy password-free sign-ins where supported. Not all websites or services currently support passkeys.
- Advanced Multi-Factor Authentication - Offers 200 FIDO2 passkey slots and 50 OATH-TOTP slots. Strong, flexible 2FA/MFA support across various apps and authentication platforms.
Rank #4
- Security Key : Protect your online accounts against unauthorized access by using FIDO2 and U2F authentication with T110. It's the world's most protective security key that works with windows, Mac OS, Linux as well as Chrome, Firefox, Edge and many other major browsers.
- Certified with the new FIDO2 standard, T110 provides the benefit of fast login and strong protection against phishing, account takeover as well as many other online attactks.
- Works with : Bank of America, Github, Google, Microsoft, DUO, Twitter, Facebook, Dropbox, Apple, ebay, BINANCE, mor and more.
- Fits USB-A port : Insert the T110 security key into the USB-A port of each service and log in conveniently with one touch
- For the driver download and user guide, please visit TrustKey Solutions Home support page.
Rank #3
- POWERFUL SECURITY KEY: The YubiKey 5 is a versatile physical passkey that protects your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5 secures 100+ of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5 via USB and tap it to authenticate. No batteries, no internet connection, and no extra fees required.
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
What to do if you see credible unauthorized access
- Stop using the potentially affected PC for sensitive work. Do not use it to access accounts or handle information that could be exposed.
- If it is managed by an employer or organization, contact its IT or security team promptly. They can determine whether the activity is authorized and coordinate a response.
- Let the responsible team handle isolation and investigation. CISA’s incident guidance for organizations calls for isolating affected systems and reviewing relevant logs and artifacts; depending on the incident, qualified incident-response support may be appropriate. The guidance addresses organizational incidents, so household users should not treat it as a universal isolation procedure. See CISA’s incident advisory.
- Do not assume that one clean scan settles the question. If there is credible evidence of unauthorized access, escalate it even if Windows Security reports no detection.
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