Windows 11 Antimalware Service Executable Access Denied

Published by Nyau Wai Hoe - Updated on

In Windows 11 or Windows 10, the Antimalware Service Executable (MsMpEng.exe) is super important for keeping your computer safe. It’s the heart of Microsoft Defender (that’s the new name for Windows Defender), which comes built into Windows 11 to fight off malware. This tool checks your files for bad stuff regularly to keep your data safe. But, it can get a bit too enthusiastic, using a lot of your computer’s CPU, memory, and disk space, even when you’re not doing much.

Trying to stop the Antimalware Service Executable or MsMpEng.exe through Task Manager usually gets you an “Access Denied” message. This happens because the service has special permissions to make sure it stays running, so even bad software can’t shut it down. But, this can be annoying if it’s slowing down your computer a lot. We’re going to talk about why this happens and share three ways to handle or turn off the Antimalware Service Executable in Windows 11.

Windows 11 Antimalware Service Executable Access Denied

Why “Access Denied” for Antimalware Service Executable in Task Manager?

The Antimalware Service Executable is a big deal in Windows 11. It’s a key part of keeping your computer safe. Here’s why you get that “Access Denied” message:

  1. Windows wants to stop you from accidentally turning off something important. This helps make sure you don’t turn off your protection against bad software without realizing it.
  2. It also makes it tough for bad software to turn off Microsoft Defender on its own. If it was easy to stop, bad software could just turn off your protection before doing nasty stuff to your computer.

Because of these reasons, when you try to stop it from Task Manager, Windows steps in with the “Access Denied” message to keep the protection going strong.

Also see: Antimalware Service Executable High Disk or CPU Usage

Method 1: Installing a third-party antivirus

One simple way to deal with the Antimalware Service Executable eating up your resources is to use a different antivirus program. Here’s the deal:

  • When you get a good antivirus from another company, Windows gets the hint and usually turns off its own Defender. This stops the two from fighting over your computer’s resources.

Install a third party antivirus in Windows 11

Here’s how to switch to another antivirus:

  1. Look around and pick a third-party antivirus that you like.
  2. Download and set up the antivirus software you chose.
  3. Restart your computer. Windows will usually notice the new antivirus and turn off Microsoft Defender for you.
  4. To make sure, go to Windows Security > Virus & threat protection. You should see your new antivirus listed as active, not Windows Defender.

Useful tip: How to Limit CPU Usage of a Process in Windows 11

Method 2: Adjusting Windows Defender Scheduled Scan in Task Scheduler

Another way to stop the Antimalware Service Executable from hogging your resources is by scheduling it to run only at certain times. You can do this with something called Task Scheduler in Windows 11 or 10:

  1. Press the Windows + R keys at the same time, type “taskschd.msc”, and press Enter.Open Task Scheduler in Windows 11
  2. Look on the left side, go to Library > Microsoft > Windows > Windows Defender.
  3. Find and double-click on “Windows Defender Scheduled Scan”.Windows Defender Scheduled Scan Task Scheduler
  4. Click on the “Conditions” tab.
  5. Check the box that says “Start the task only if the computer is idle for:” and pick how long you want to wait. This makes sure the scan only runs when you’re not using your PC.MsMpEng.exe Access Denied Windows 11

Method 3: Disabling Windows Defender with a script suggested on Reddit

Some folks who really know their way around computers share tricks online for customizing Windows more than usual. One trick is using a special script to turn off Microsoft Defender completely. But, using this script isn’t easy because it needs special permissions. You’ll also need a tool called NSudo.

Related resource: How to Reinstall Windows Defender in Windows 11

Why do we need NSudo?

The script has to run with the powers of the TrustedInstaller user. This user has special access to mess with system files and processes that even admins can’t touch. NSudo lets you run stuff with those TrustedInstaller powers.

Steps to completely disable Windows Defender

Here’s how to turn off Microsoft Defender using that script and NSudo:

  1. Get the script ready:
    • Go to this Pastebin link.
    • Copy the script and paste it into Notepad.
    • Save it as a .bat file, like “disable_defender.bat”.
    • Save it as a .bat file, like “disable_defender.bat”.Script to completely disable Windows Defender
  2. Set up NSudo:
    • Get NSudo from a trusted source or
    • Unzip the file you downloaded to a place you can find easily.NSudo Launcher
  3. Use NSudo to run the script:
    • Open the NSudo folder, look for NSudo Launcher > x64.
    • Open the NSudoLG.exe file.How to run NSudo Launcher in Windows 11
    • Make sure “Enable All Privileges” is checked.
    • In the NSudo Launcher window, click “Browse”.
    • Hit “Run” to start the script.Completely disable Antimalware Service Executable Access Denied
    • The script will do its thing with TrustedInstaller powers and turn off Microsoft Defender.
  4. Make sure it worked:
    • Restart your PC.
    • Check if Microsoft Defender is turned off now.

Be careful: Turning off Microsoft Defender this way means you’re losing a big chunk of protection for your computer. Make sure you have some other strong antivirus or security program running if you decide to go this route.

Wrapping it up

The “Access Denied” message you see when trying to stop the Antimalware Service Executable in Windows 11 is really there to help protect your computer. But, it can also make things a bit slow, especially if you’re playing games or running big programs. While there are ways to get around this, like turning off the feature, it’s important to do this carefully. Using the script is really a last-ditch effort. And remember, turning off built-in protection is risky. Always have another good antivirus ready to keep your system safe from bad stuff.

Nyau Wai Hoe
Nyau Wai Hoe is the Founder and Chief Editor of With a degree in software engineering and over 12 years of experience in the tech support industry, Nyau has established himself as an expert in the field, with a primary focus on the Microsoft Windows operating system. As a tech enthusiast, he loves exploring new technologies and leveraging them to solve real-life problems.

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