The Microsoft Windows Malicious Software Removal Tool

If you’ve ever looked over the regular updates that get delivered the second Tuesday of every month (so-called “Patch Tuesday”) to your Vista machine, you can’t help but have noticed the regular appearance of something called the Windows Malicious Software Removal Tool. As I write this blog on 8/05/2008, it’s only the first Tuesday of the month, so the latest version is dated 7/8/2008, as documented in KB article 890830 (there’s also a download).

After reading that this tool resides in %windir%System32, in a file named mrt.exe, I checked mine and found that I couldn’t run the program for some reason or another, and that the version installed was dated 1/8/2008. So I visted the aforementioned download link and installed the 7/8/2008 version manually on my machine. I started of with the quick check scan, which completed in less than a minute on my machine (and found nothing), and then launched a scan at the command line (mrt.exe /F:Y, to force a full scan, and to instruct the tool to fix any infections it might find).

Even Microsoft says you shouldn’t use this free program in lieu of a real anti-virus/anti-spyware tool. There are lots of reasons why this is a perfectly valid thing to say, starting with the tool’s inability to provide real-time protection for e-mail attachments, file downloads, and so forth, and ending with its abysmally slow complete system scan time (on my system PC Doctor usually takes under 20 minutes to scan everything, and my AVG Anti-Virus usually finishes up in under 25 minutes. As I write this piece, the MRT full scan has been running for 31 minutes and is less than one-third complete, according to its progress bar. Note: it took just over 80 minutes to complete!).

MRT full scan underway

MRT Full scan underway at 24:01 into the process

That said, the MRT can find and fix current virus and spyware infections, and should be part of the security/maintenance toolkit you call on when the time comes to look for or diagnose potential malware problems. While it shouldn’t be your only anti-malware tool, the latest version should be part of your toolbox any time you go looking for malware trouble. Visit Microsoft Support, and search on “download Windows Malicious Software Removal Tool” any time, to provoke a link to the current version.


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