Kenzero virus is delivered by downloading an adult video game. (Terry Reith/CBC)

A new Internet scam circulating in Japan is among the latest ploys by cyberthieves to extort cash from unsuspecting web users.

The Kenzero virus originates from a Japanese downloading site and is embedded in a file that's posing as an adult video game, says Internet security company Trend Micro.

Users are prompted to enter their personal information before the game installs but meanwhile, the virus is actually scanning their computer for data. Soon, they receive an email linking to a website where they're told to pay up or have their name posted on a public list of people who bought the raunchy game.

"It's probably scaring a few people and if you tell them, 'Pay that much and you'll be off the list,' some people will actually do that," said Jerome Segura, a security analyst with the Victoria-based security company ParetoLogic.

The Kenzero scam falls within a subcategory of viruses called "ransomware."

One of these ransomware viruses adds pornographic icons to a user's desktop and when the user tries to delete them, they're presented with a pop-up window with a legitimate-looking ad to purchase antivirus software. Users who take the bait lose their money and may subsequently have their credit card information sold on the black market.

Another emerging virus is hidden within music or movie downloads and produces prompts that accuse the user of copyright infringement and demands payment for the offence. Sometimes the user's desktop background is changed to the FBI logo along with a serious-sounding threat for greater effect, Segura said.

Having antivirus software does not necessarily make users immune to the latest ransomware scams and other viruses, Segura warned.

"It's something that they miss a lot of the time because this type of [ransomware virus] comes from sites that use a polymorphism, which means they basically randomize the file they send you and it gets by well-known antivirus products very easily," he said.

"I've seen people firsthand getting infected, having all the pop-ups and yet they have antivirus software running and it's not detecting anything.

"It actually can be pretty hard to get rid of, as well, and you're never really sure if it's really gone. When we see something like that usually we advise to reinstall the operating system or reinstall backups."