There are times when viruses or other malware prevent Windows from working as it should. In this situation, you may not be able to access or use Microsoft Defender scan or even a third-party virus scanner.
Fortunately, Microsoft has an external tool that you can use to scan and find your Windows system for malware: Microsoft Safety Scanner.
Why use the security scanner and not Microsoft Defender?
The Microsoft Safety Scanner tool is not a replacement for Microsoft Defender under normal circumstances. If your computer is working normally and a Defender scan can be used, then it should be used.
However, if you cannot use Microsoft Defender to scan for threats, the Safety Scanner tool can be used instead. The tool doesn’t need to be installed, so it can come in handy when your Windows system or Defender is having problems.
Learn more about using Microsoft Defender to scan your computer for malware.
How to scan Windows with security scanner
You can download the Safety Scanner tool from the Microsoft website. Both 32-bit and 64-bit versions are available, so make sure you choose the right one for your system.
The scanner tool is a portable app and therefore does not need to be installed. It can be run from the desktop or download folder. It can even be run from a removable drive.
- To start, double-click the MSERT icon in its download location to run the app.
- Accept the license agreement and click Next. The following screen contains the available scan options.
- You can choose a quick scan, a full scan, or a custom scan. Aside from an offline scan, these are the same scanning options as in Defender.
- Select the scan you want and click Next. If you choose one Custom scanyou also need to select the folder you want to scan.
- The scanning time depends on the scan type and the number of files to be scanned.
You can view a detailed log of the scan results in the C:\Windows\debug\ folder. The file path will be different if you installed Windows to a location other than the default location. Find and open the msert.log File in Notepad or a similar text editor.
Speaking of which, if you want to open Notepad quickly and easily, check out how to add an “Open with Notepad” option to the Windows context menu and save yourself a few clicks.
What to do if Safety Scanner finds malware
Microsoft Safety Scanner does not remove any malware it finds, but it does show you suspicious files and where to find them. Navigate to the file location shown and identify the suspicious file.
You can then check the Microsoft Malware Protection Center to see if the file is known malware. And how best to remove it from your computer manually.
What are the limitations of the Microsoft Safety Scanner?
Once downloaded, the scanner can only be used for 10 days. After that it has to be downloaded again. This prevents the security definitions it contains from becoming obsolete. It also helps bring the concept of its design home as a tool for casual use.
As mentioned above, the tool does not remove or quarantine the threats for you. You must find the infected file(s) and remove them yourself. This is usually just a case of deleting the identified files.
The scanner may occasionally display error codes, either before or after a scan is complete. Some of the most common are:
- 0x80508019 – The scan target file or drive does not exist.
- 0x80508007 – There is not enough memory to complete the operation.
- 0x80508024 – A full scan is required.
- 0x80508001 – The scan engine could not be loaded.
Scan for malware with Microsoft’s Safety Scanner
Having an alternative way to scan for malware can be incredibly useful if something goes wrong with Defender or your chosen third-party malware scanner. Microsoft Safety Scanner isn’t a permanent replacement for your other security tools, but it’s a useful app to know about.