Microsoft Windows Defender Review

All Windows 8 PCs come preloaded with Windows Defender, Microsoft's own antivirus software suite. It's the successor to both Microsoft Security Essentials — an optional antivirus suite for Windows XP, Vista and 7 — and a separate Microsoft anti-spyware program, which, confusingly, was called Windows Defender in earlier versions of Windows.

History lesson aside, how useful is Windows Defender for Windows 8 and 8.1? Although it may be free, our tests show that it isn't very effective. Even among free antivirus programs, you can do far better than relying upon Windows Defender.

Setup and interface

Windows Defender does win the "easiest setup" category among free antivirus software, simply because all Windows 8 machines come with it preinstalled. On our Windows 8 Acer Aspire E1 laptop, we tapped the Windows and C keys to launch the Search option, and typed "Defender" to find the program.

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After doing that, some users may see a message saying, "This app has been turned off and isn't monitoring your computer." You may have another antivirus program already running, such as a 90-day "trialware" version of a paid antivirus suite that many computer makers ship with their machines.

If that's not the case, then turn on Windows Defender by opening the Windows 8 Action Center (type "Action Center" into Search), and click Turn On Now.

The Windows Defender interface is plain, simple and functional. Tabs along the top of the interface let users navigate the Home, Update, History and Settings screens.

MORE: How to Install and Use Malwarebytes Anti-Malware

The Home screen is the most useful: It has an icon that's colored green when your computer is secure, yellow when it may be at risk and red if malware is detected. From the main user interface, you can activate a full scan, quick scan or custom scan.

Features and tools

Like most free antivirus software, Windows Defender offers real-time protection and will alert you when it detects malware trying to install itself on your computer. Other than that, Windows Defender offers a bare minimum of anti-malware features, without extra bells and whistles.

You can automatically schedule scans in Windows Defender, but the option isn't anywhere on the program's interface. Instead, you have to go into your PC's settings and use the Task Scheduler, which can be found under Administrative Tools.

After a scan, Windows Defender will put any problematic files that it detects into Quarantine, which is an isolated and secure storage location on your computer. You can then decide to delete the files or restore them by going to the History tab, selecting Quarantined Items and then clicking the View Details button.

Windows Defender is proactive, meaning it can catch malware in real time as it tries to install on your computer. Among the free antivirus tools we've tested, only Malwarebytes Anti-Malware is not proactive; it's simply a cleaning tool for getting malware out after it's already installed.

Windows Defender has no other extra features. In contrast, Avira Free Antivirus and Avast Free Antivirus scan Web URLs for any malicious code; AVG Antivirus Free has tools to improve the PC's performance; and Malwarebytes Anti-Malware has a great feature called Chameleon for wresting back control of a PC from even the most aggressive malware.

Security performance

Microsoft Defender generally performs the worst — by far — of any free or paid antivirus program in recurring evaluations conducted by independent German lab AV-TEST. In an April 2014 round of tests, Windows Defender's ability to detect cutting-edge malware threats was considerably subpar; it detected only 68 percent of zero-day Web and email threats against an industry average of 94 percent.

Windows Defender also performed below average in detecting widespread, commonly known malware; it detected 79 percent of those bugs, compared with the industry average of 98 percent. In comparison, Avira Internet Security (a paid version of Avira's antivirus product) scored a perfect 100 in detecting both zero-day and widespread malware, and Avira told us that Avira Free Antivirus offers the same protection.

AVG Antivirus Free came in first among free antivirus software programs tested by AV-TEST, detecting 96 percent of zero-day malware and 99 percent of widespread malware. Avast Free Antivirus got 94 percent of the zero-days and 98 percent of the common malware. Malwarebytes Anti-Malware is not evaluated by AV-TEST.

APRIL 2014

Zero-Day Malware

Widespread Malware

Avast Free Antivirus



Avira Internet Security (paid)



AVG Antivirus Free



Windows Defender



Malwarebytes Anti-Malware



Industry average (free and paid)



System impact

Nobody wants to use an antivirus program that drastically slows down a PC when it scans. That's why we tested all products in this category for performance impact. In this area at least, Defender is competitive.

The performance-testing software PCMark7 gave our Windows 8 Acer Aspire E1 a baseline score of 2,105. When we ran the benchmark test while also running a quick scan on Windows Defender, that performance score actually rose to 2,145, the best quick-scan score of any of the free antivirus products we've tested. During a full scan, however, the performance score dropped to 1,677, the middle of the range among the other four free antivirus programs.

We also tested each antivirus product using our own OpenOffice performance test. As a baseline, the Acer Aspire E1 matched 20,000 names and addresses in 4 minutes. While Windows Defender's quick scan was running, the laptop completed the test in 5 minutes. While Defender's full scan ran, the test completed in 10 minutes and 30 seconds. That's behind AVG and Avast, but ahead of Malwarebytes and Avira. (See times below.)

PCMark7 Quick Scan

PCMark7 Full Scan

Custom Test Quick Scan

Custom Test Full Scan

Avast Free Antivirus





Avira Free Antivirus





AVG Antivirus Free





Windows Defender





Malwarebytes Anti-Malware





Bottom line

Many people rely on Windows Defender because they don't want to pay for security. But other free products prove that you don't have to spend a dime to beat Windows Defender's feeble malware detection and limited features. Avira Free Antivirus, Avast Free Antivirus or AVG Antivirus Free will all serve you better than Defender can.

Installing Malwarebytes Anti-Malware, which is meant to complement antivirus software, will help a bit if you opt to settle for Windows Defender. (We recommend you run Malwarebytes Anti-Malware alongside whichever free or paid antivirus program you choose.) When it comes down to it, Windows Defender just doesn't live up to its name.

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  • malwarebytes and windows defender are great together.
    tom obviously got paid for this article just look at his adverts.
  • Windows Defender is basically the same thing as MSE it offers the same level of protection, i think the thing where Windows users get confused is MSE and the new Windows Defender is differnt than the old Defender. the old version is anti malware MSE and Windows Defender are Microsoft's version of an Antivirus, it's not most effective but it's all you need. +Malwarebytes. If you suspect a virus, Update Defender and run full scan to be most effective.
  • Windows Defender is not enough, even with Malwarebytes Anti-Malware running as the cleanup crew. Believe us. If you don't want to pay for AV software, try Avira, AVG or Avast, which are as, or almost as, good as the paid stuff.