Have you ever received a phone call from someone claiming to be from Microsoft who says he's detected a virus on your computer and, for a certain fee, he can fix it for you? If so, that's most likely a scam. And it's one that Microsoft is now trying to fight through legal means.

On Thursday, Microsoft's Digital Crimes Unit filed a civil lawsuit in the Central District of California against a company called Omnitech Support and other firms for "unfair and deceptive business practices and trademark infringement." In the suit detailed in a blog posted on Thursday, Microsoft charges that Omnitech Support, a division of Customer Focus Services, has misused the Microsoft name, trademarks and service, all in an attempt to scam consumers out of money or personal information by pretending that their PCs were infected by malware.

These types of scams follow a familiar pattern: Someone calls you up and claims to be from Microsoft or a Microsoft partner. The person says that he's somehow detected a virus on your computer. The scammer then convinces you to install remote control software on your PC so that he can gain actual access to it. Once the scammer is able to control your PC, he typically installs some type of scareware that simulates a virus. From there, the person tells you that he can fix the problem, but only if you pay a certain fee. If you agree, the scammer then gains access to your credit card information and often other personal information.

"In some instances, Omnitech has actually created security issues for victims by gaining access to their computers and installing malicious software, including a password grabber that could provide access to personal and financial information," Microsoft said in its blog.

To back up its legal case, Microsoft used investigators who made contact with the defendants named in the lawsuit. In each case, the investigators worked with a computer that did not contain any viruses or malware. But each defendant claimed that the computer was infected by malware or that Windows was corrupted and as such wanted to charge a large fee to fix the issue.

Many customers who were affected by one of these scams contacted Microsoft to complain that their computers were in worse shape after the scammers got through with them. In its legal brief, Microsoft said it believes that Americans lose around $1.5 billion each year as a result of these scams.

Microsoft summed up its complaint against the defendants through the following statement in its legal brief:

Defendants have, without authorization, used and misused the Microsoft name and Microsoft's registered trademarks and service marks in commerce in connection with the provision of phony technical support services. Defendants have utilized the Microsoft trademarks and service marks to enhance their credentials and confuse customers about their affiliation with Microsoft. Defendants then use their enhanced credibility to convince consumers that their personal computers are infected with malware in order to sell them unnecessary technical support and security services to clean their computers. In some instances, Defendants actually create security issues for consumers by gaining access to their computers and stealing information stored on them.
Due to the actions of the defendants, Microsoft charges that it has suffered a loss of goodwill and is seeking a permanent injunction on the actions of the defendants as well as financial damages. As part of the civil suit, Microsoft is asking the court for a jury trial.

A Microsoft spokesperson told CNET that the company had nothing more to share beyond what was revealed in the blog post. Omnitech Support did not respond to a request for comment.