Windows Malicious Software Removal Tool (MSRT) helps keep Windows computers free from prevalent malware. MSRT finds and removes threats and reverses the changes made by these threats. MSRT is generally released monthly as part of Windows Update.
There are a couple of things that can cause this high CPU usage from the mrt.exe process. Mrt.exe (Malicious Software Removal Tool) is, in fact, a Windows own removal tool. So, if you see the mrt.exe running in the Task Manager then it doesn’t always mean that it is a virus. The Malicious Software Removal Tool is updated via the Windows Update every month (in the Tuesday update of every month). This tool is designed to run whenever it is updated but it shouldn’t run after that. In fact, it won’t run for the whole month or until the next time it is updated. So, if you see mrt.exe using high CPU just once or every once in a while then you probably don’t have to worry. It is normal for mrt.exe to consume a lot of resources. So, as long as it doesn’t always run then you don’t really have to worry. However, if you see mrt.exe running continuously for days then that is a red flag. Since mrt.exe isn’t supposed to run all the time or at least every day, there might be a virus pretending to be mrt.exe in the Task Manager.

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