Because Windows operating system has been the main target of the malware (malicious software), Microsoft released a tool called Malicious Software Removal Tool in order to help the Windows users get rid of a huge range of the malware families. The Microsoft malicious software removal tool checks computers running Windows 8.1, Windows 8, Windows 7, Windows Vista, Windows XP, Windows 2000, and Windows Server 2003 for infections by specific, prevalent malicious software — including Blaster, Sasser, and Mydoom — and helps remove any infection found. Microsoft releases a new version of the tool every month containing definitions to remove newer malware. When the detection and removal process is complete, the tool displays a report describing the outcome, including which, if any, malicious software was detected and removed.
You can download the malicious software removal tool from the web site at http://www.microsoft.com/en-us/download/malicious-software-removal-tool-details.aspx. Because this file is updated every month, so you should always download a new file. The download is in form of an executables. The filename is in the form of Windows-KB890830-x64-V5.9.exe. To run the tool, just double-click on this file. You need to have the administrator level privileges to run the tool.
The first window you would see gives you basic information about the Malicious Software Removal Tool including online links to the documentation, a list of malware that it is able to eradicate from your PC etc. You have to click the Next button in order to proceed.
Now you will land on a window asking you to choose a type of scan. You can choose from the quick scan, full scan and customized scan. The quick scan scans only the key areas of your system which are more likely to get infected with malware. The full scan scans whole of your system and consequently can take many hours to finish up scanning. The customized scan is same as the quick scan with one added option to scan some customized folders. It is recommended that you choose the Full scan and then click Next to proceed.
The scanning operation may take many hours to complete depending on the size of your hard disk and the number of programs you have installed on your computer. When the malware is found, the Microsoft malicious software removal tool will automatically remove all the detected malware. You will be shown a final window telling you that malware was found and removed. You can click on the View detailed results of the scan to see the detailed report of the scanning and the removal.
If you choose to see the details, you will see another window showing a list of malware families that the malicious software removal tool can detect and remove. You can see under the scan results column whether the malware was detected (found or not found), removed completely or removed partially. On my test computer it found many different versions of the Zbot malware and they were removed only partially.
You can click the Finish button to close the tool. If any malware is found, it is recommended that you scan again with the full scan setting (if you performed the quick scan earlier). The Microsoft malicious software removal tool is not a replacement for a regular stay-resident antivirus product. You can use this tool for emergency removal of many malware types but you should also install a full antivirus product like avast! free antivirus to protect your system from future malware infections.
Conclusion: The Microsoft Malicious Software Removal Tool is very useful in detecting and removing the common malware families. In some cases, it can detect even those malicious files which stayed untouched by your regular antivirus products. But in any case, it is not a replacement for a regular antivirus.