Support for Windows 7 ended on January 14, 2020
We recommend you move to a Windows 11 PC to continue to receive security updates from Microsoft.
What is Microsoft Security Essentials?
There are a host of nasty intruders on the Internet including viruses, trojans, worms and spyware. Microsoft Security Essentials offers award-winning protection against these intruders without getting in your way.
The best brains and brawn in the background
Microsoft Security Essentials is built for individuals and small businesses, but it’s based on the same technology that Microsoft uses to protect giant businesses (security products like Microsoft Forefront, the Malicious Software Removal Tool, and Windows Defender). We have a whole team watching for new threats and coming up with ways to squash them.
We’re proud to have received great recognition for the protection we offer: the VB100 award from Virus Bulletin Ltd., Checkmark Certification from West Coast Labs, and certification from the ICSA Labs.
Easy to get, easy to use
Downloading and installing Microsoft Security Essentials is free* and easy. Once you have installed it, the software updates automatically once a day. We’re constantly tracking new threats and we keep your PC updated to help protect you. You don’t have to do anything.
Microsoft Security Essentials uses green, yellow and red color codes to designate the security status of your PC and a color-coded icon in the taskbar tells you at a glance if your attention is needed. It’s simple—when you’re green, you’re good. However, if there’s a red or yellow threat, Microsoft Security Essentials will alert you and recommend what to do (you can act directly from the notification area without having to enter the application).
Runs quietly without hurting PC performance
Microsoft Security Essentials runs quietly in the background. You’ll only be alerted when there are specific actions to take. When you’re away or busy, Microsoft Security Essentials can take the default action on your behalf and you can open the program later to review and undo those actions if you wish.
Microsoft Security Essentials is efficient and compact. Scans and updates are scheduled to run when the PC is idle and the software works in a way that your PC is still snappy when you’re using it. All this makes Microsoft Security Essentials friendly for all sorts of computers—your old PC, your new PC, your laptop, as well as your little netbook.
Features and benefits
Why get Microsoft Security Essentials?
Microsoft Security Essentials is world-class security for your PC that's free* and easy to download. Here are some ways Microsoft Security Essentials helps keep your PCs safe without getting in your way or making you worry.
Real-time protection means addressing potential threats before they become problems. Alerts notify you when spyware, viruses, or other malicious software attempt to run or install on your PC, and suspicious files and programs are prevented from opening.
Microsoft Security Essentials offers complete system scanning capabilities with both scheduled and on-demand scanning options to provide an extra level of confidence. Scheduled scans are turned on by default and configured to run weekly at 2 a.m. when the system is likely idle. There are three scanning options:
Quick Scan. by default, a quick scan rapidly checks the areas malware is most likely to infect, including programs running in memory, system files, and the registry.
Full scan. A full scan checks all files on the PC, the registry, and all currently running programs.
Custom scan. A custom scan allows you to scan only the areas you select.
You can choose when you want a scheduled scan to run, view the scan results before cleaning, or run a scan on demand. If the PC isn't turned on when the scan is scheduled to run, Microsoft Security Essentials will start the scan at the first opportunity once the PC is awake and idle.
When Microsoft Security Essentials determines a possible threat on your PC, alerts notify you of the threat. Threats are categorized as Severe, High, Medium, or Low, and you can choose whether to ignore, quarantine or remove the item from the system.
Quarantine. Microsoft Security Essentials blocks less severe threats and moves them to a quarantined queue where you can elect to restore or permanently delete them. By placing an item in quarantine, you can test the effect of the item’s removal before deleting it from the system.
Remove. This action permanently deletes the item from the system.
Allow. This action stops Microsoft Security Essentials from detecting the item in future scans by adding it to the Allowed Items list. You can remove items from the Allowed Items list at any time.
Having an active firewall is part of securing your PC. During setup, Microsoft Security Essentials scans the PC to determine if a firewall is active on the PC. If no firewall protection is present, you'll be given the option to turn on Windows Firewall.
Protection needs to be up-to-date to be effective. Dynamic signature is a way to check whether a suspicious program is bad or not. Before a suspicious program runs, Microsoft Security Essentials pretends to run it to determine what it’s going to do. This gives programs special signatures that are checked against our database of good and bad programs. Programs are watched even after they are approved to make sure they don’t do anything potentially harmful like make unexpected network connections, modify core parts of the operating system, or download malicious content.
To find information, definition updates, and analyses of all the latest threats that Microsoft Security Essentials can help protect you against, visit the Microsoft Malware Protection Center.
Rootkits are particularly difficult types of malware to protect against, and Microsoft Security Essentials includes a number of new and improved technologies to address rootkits and other aggressive threats.
The kernal is at the heart of your PC’s operating system. Microsoft Security Essentials monitors it to see if there are any attacks or harmful modifications.
Rootkits use stealthy methods to hide themselves and Microsoft Security Essentials has the latest anti-stealth technology to uncover them. For example, direct file system parsing helps find and remove malicious programs and drivers that rootkits try to sneak in.
Microsoft Security Essentials helps block bad software. We keep a list of the most popular websites and downloads on the Internet and use it to test our antimalware definitions and updates before they get to you. This helps us make sure that the protection we offer really keeps your PC safe, and not blocked.
The new Windows comes with Windows Defender
Windows Defender for Windows 10, Windows 8.1, Windows RT 8.1, Windows 8, and Windows RT provides built-in protection against malware. You can't use Microsoft Security Essentials, but you don't need to—Windows Defender is already included and ready to go. But if you’re looking to protect a PC with an older version of Windows, you can use Microsoft Security Essentials to help guard against viruses, spyware, and other malicious software. It provides real-time protection for your home or small business PCs.
Minimum system requirements for running Microsoft Security Essentials
Microsoft Security Essentials is free* and easy to download and use. Here's what you need to run it:
Operating System: Windows Vista (Service Pack 1 or Service Pack 2), Windows 7
A PC with a CPU clock speed of 1.0 GHz or higher, and 1 GB RAM or higher.
VGA display of 800 × 600 or higher.
200 MB of available hard disk space.
An Internet connection is required for installation and to download the latest virus and spyware definitions for Microsoft Security Essentials.
Windows Internet Explorer 6.0 or later.
Mozilla Firefox 2.0 or later.
Note: As of April 8, 2014, technical support for Windows XP and Windows XP Mode are no longer available, including updates that help protect your PC. Learn more about Windows XP end of support.