Microsoft Defender Antivirus?

Question

I have been attacked by a blocker of some sort and I can't open executable files among others. I need Windows/Microsoft Defender Antivirus to scan my Win10 Desktop and provide Firewall capability as well. Please help. Thank you.

Answer 1

Follow https://support.microsoft.com/en-us/windows/security/windows-security/stay-protected-with-the-windows-security-app

To open the  Windows Security app  , search for it in the Start menu.

Open Windows Security

Common tasks

Here's a brief list of common tasks that you can carry out from the Windows Security app. Expand each section to learn more:

Run a malware scan manually

If you're worried about a specific file or folder on your local device, you can right-click the file or folder in File Explorer, then select Scan with Microsoft Defender.

Tip

On Windows 11 you may have to select Show more options after you right-click to see the option to scan the file or folder.

Run a quick scan

If you suspect there's malware or a virus on your device, you should immediately run a quick scan. 

In the Windows Security app   on your PC, select Virus & threat protection > Quick scan or use the following shortcut:

Start a quick scan

If the scan doesn't find any issues, but you're still concerned, you may want to check your device more thoroughly.

Turn Defender Antivirus real-time protection on or off

Sometimes you might need to briefly stop running real-time protection. While real-time protection is off, files you open or download won't be scanned for threats. However, real-time protection will soon turn on automatically again to protect your device.

In the Windows Security app   on your PC, select Virus & threat protection > Manage settings or use the following shortcut:

Virus & threat protection settings

You can turn Real-time protection On or Off using the toggle button.

For firewall setup instructions, refer to https://support.microsoft.com/en-us/windows/security/windows-security/firewall-and-network-protection-in-the-windows-security-app

Configure Windows Firewall with Windows Security

1. In the Windows Security app   on your PC, select Firewall & network protection or use the following shortcut: Firewall & network protection
2. Windows Security shows you which type of network you're currently connected to. Usually, your device will only be connected to one network at a time. Select a network profile: Domain network, Private network, or Public network.
3. Under Microsoft Defender Firewall, switch the setting to On to enable Windows Firewall. To turn it off, switch the setting to Off. Turning off Windows Firewall could make your device more vulnerable to unauthorized access. If there's an app you need to use that's being blocked, you can allow it through the firewall, instead of turning the firewall off.
4. Under the Incoming connections section, there's a checkbox for Blocks all incoming connections, including those in the list of allowed apps. Checking this box tells the Windows Firewall to ignore the allowed apps list and block everything. Turning this on increases your security but might cause some apps to stop working.

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hth

Marcin

Answer 2

If executable files cannot be opened and Windows Security is affected, use the built-in Microsoft Defender tools in this order:

1. Open Windows Security from the Start menu.
2. Go to Virus & threat protection.
3. Under Virus & threat protection settings, select Manage settings and make sure these are On:
   • Real-time protection
   • Cloud-delivered protection
   • Automatic sample submission
4. In Virus & threat protection, select Quick scan first.
5. If the problem continues, select Scan options and run Windows Defender Offline scan.
   • This is important when malware keeps returning or hides while Windows is running.
   • Warning: the PC will restart before the offline scan starts, so save work first.
6. If Defender still does not detect or remove the threat, run the Microsoft Safety Scanner.
   • After the scan, detailed results are in %SYSTEMROOT%\debug\msert.log.
7. For firewall capability, use the Windows Security app, which includes Windows Firewall as part of the built-in protection experience.
8. If another antivirus or antispyware product is installed, uninstall it before relying on Microsoft Defender Antivirus for real-time protection.
   • Running more than one real-time security product at the same time can reduce performance and can cause update or install errors such as 0x80070643.
9. If Microsoft Defender Antivirus was disabled and there is no other active security product, it can turn on automatically. It can also be enabled manually from: Start > Settings > Update & Security > Windows Security > Virus & threat protection > Manage settings > Real-time protection.

If malware keeps coming back after removal, avoid reopening files or revisiting sites that delivered the infection, and use Microsoft Defender Offline again to catch hidden components.

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• Antivirus and antimalware software: FAQ
• Stay protected with the Windows Security app
• How to start a scan for viruses or malware in Microsoft Defender
• Troubleshoot problems with detecting and removing malware
• Microsoft Defender Antivirus in the Windows Security app
• Microsoft Safety Scanner Download