Microsoft Security Essentials is a free download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It's easy to tell if your PC is secure --- when you're green, you're good. It's that simple.

Your PC must run genuine Windows to install Microsoft Security Essentials. MSE requires Windows 7, Windows Vista, or Windows XP.

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. 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).

Real-time protection

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.

System scanning

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.

System cleaning

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.

Windows Firewall integration

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.

Dynamic signature service

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.

Rootkit protection

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.

Protection against real threats, not good software

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.

Network inspection system

The latest version of Microsoft Security Essentials helps you keep your PC network safe, too. The network inspection system protects against programs like Conficker (MS09-67) and others that exploit network vulnerabilities to infect PCs.

What's New:

  • Added Prerelease 4.6.0205.0 to download links.