Each release of the tool helps detect and remove current, prevalent malicious software. This malicious software includes viruses, worms, and Trojan horses. Microsoft uses several metrics to determine the prevalence of a malicious software family and the damage that can be associated with it.

One of the most common ways of transmitting computer viruses is through file attachments. To help protect you and your recipients against computer viruses, Outlook blocks the sending and receiving of certain types of files (such as .exe and certain database files) as attachments.

If some Windows functions aren't working or Windows crashes, use the System File Checker to scan Windows and restore your files. Though the steps below might look complicated at first glance, just follow them in order, step-by-step, and we’ll try to get you back on track.

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you're blocked from installing or removing programs. It also fixes corrupted registry keys. First, you'll need to download the troubleshooter. Download troubleshooter.

Microsoft is aware of new variants of the class of attack known as speculative execution side-channel vulnerabilities. The variants are named L1 Terminal Fault (L1TF) and Microarchitectural Data Sampling (MDS). An attacker who can successfully exploit L1TF or MDS may be able to read privileged data across trust boundaries.

Remote Assistance Support from Microsoft allows a Microsoft support professional in another location to view your computer screen and work on your computer over a secured connection. Protect yourself from tech support scams. Before clicking 'I accept', review the: Agreement for Microsoft Services. Microsoft Software License Terms.

Follow these steps to automatically diagnose and repair Windows security problems by turning on UAC, DEP protection, Windows Firewall, and other Windows security options and features. Select the Download button on this page.

No restrictions to types of files added to SharePoint. Recent improvements in SharePoint in Microsoft 365 and SharePoint Server 2019 have removed the limitations on types of files that can be added. There are currently no known types of files that cannot be added.

Learn how to remove malware from your PC. Use Microsoft Defender Antivirus in Windows 10 or Windows 11 to scan your PC for malware, viruses, or other threats.

Learn how to change default apps and protocol handlers in Windows, including an example about how to configure the default browser.