Social networking website Facebook, which offers its subscribers a "like" button for anyone's updates, is now faced with a fake "dislike" button, which is spreading like a virus across the site.
The fake dislike button is followed with a link that takes people to a fake application. Instead of installing a dislike button, the application uses the person's network to continue spreading the fake program.
Graham Cluley of the British security firm Sophos wrote in a blog that the fake dislike buttons "are going viral" on Facebook.
"Watch out for posts that look like this: I just got the Dislike button, so now I can dislike all of your dumb posts!" CNN quoted Cluley as writing in the blog.
"If you do give the application permission to run, it silently updates your Facebook status to promote the link that tricked you in the first place, thus spreading the message virally to your Facebook friends and online contacts," he wrote.
A message on technology blog Mashable said: "As usual, we advise you not to click on suspicious links on Facebook, especially if they promise something that sounds impossible or unlikely. Do not give away your personal information, unless you're absolutely sure why and who you're giving it to."
Cluley said the fake dislike button is part of a recent trend of Facebook scams. "It's the latest survey scam spreading virally across Facebook, using the tried-and-tested formula used in the past by other viral scams."
Such schemes are designed to steal information from internet users. That information then can be sold to other parties. The scams are also used to affect an internet user's social network contacts.
The experts give the following advice to avoid the fake button: "If you accidentally installed the fake application, click on the 'account' button at the top right of the Facebook home screen. Navigate to the option that says 'application settings' and disable the fake 'dislike' application."
"If the application is posted to your Facebook wall, go to your profile page and delete those posts to stop the scam from spreading further."
Facebook has said it is trying to block the "dislike" button.
"We're working hard to block and remove malicious applications that claim to provide dislike functionality and inadvertently update people's statuses," a Facebook spokesman said.
"There is no official dislike button. Also, don't click on strange links, even if they are from friends, and notify the person and report the link if you see something suspicious," the statement said.