Clicking on the malware warning takes a user to a website offering fake antivirus software known as "Win7 AV." The website itself is also a ringer for Microsoft's, down to the airy design and stock photographs of happy looking people in front of a laptop. But it's a scam.
Better known as fake AV, or scareware, such attacks use bogus virus scans to scare users into purchasing useless software that promises to eradicate the viruses or malware the software has purportedly identified. But no such malware exists on the PC, or if it should happen to, the software doesn't actually eliminate it. In short, it's a social engineering attack.
Unfortunately, the Rogue:MSIL/Zeven attack can be difficult to spot, owing to the careful design of its browser-appropriate warning pages. According to an analysis written by the Microsoft Malware Protection Center's Daniel Radu, "the similarity between the fake warning pages is so accurate that it can trick even [the] highly trained eye."
But there are some giveaways. For example, the attackers left a misspelling in the fake Firefox warning page's "get me our of here and upgrade" button. In addition, none of the real browsers' malware and virus warning alerts ever attempt to sell antivirus software or upgrades.
In fact, said Radu, while the software attempts to sell people a fake copy of Microsoft Security Essentials, the real one, which provides antivirus and anti-malware protection for Windows, is actually free.
Appropriately, it also detects the Rogue:MSIL/Zeven malware, as well as the application that attempts to download it.