Facebook is now the hub of social networking on the web, but the site's popularity makes it ground zero for crime, and one of the hottest things on the Internet black market could be your Facebook ID.
"It is kind of scary. I've had a number of people try to friend me on facebook that I have never heard of before," said Cara, a Facebook user.
She's not alone.
Over the past few months thousands of Facebook users report receiving messages or requests from people they don't know personally.
Researchers at Verisign, an internet security company, say their researchers have tracked a growing trend of bogus and/or stolen Facebook accounts that are now up for sale in high volume on the black market.
"I think I'm definitely threatened by it," said Cara, a Facebook user.
She has a right to be worried.
Verisign says 1.5 million Facebook accounts appear to be for sale.
Criminals apparently steal log-in data for accounts, typically with “phishing” techniques that tricks users into disclosing their passwords. Then they use the accounts to send spam, send out malicious programs or steal a person's identity.
Researchers found the upsurge in February, the same time Facebook altered security settings.
Cara says the change came without warning for her and may have exposed her to people she rather not connect with.
"I'm uncomfortable knowing that anyone in any network could see my profile for a number of weeks there, because I was completely unaware," according to Cara, a Facebook user.
Facebook says it has sophisticated system to defeat fake accounts, and monitors unusual activity, like many friend requests in a short period of time or high rates of friend requests that are ignored.
Experts says the best thing to do is know who you friend, keep your personal information limited, and make sure you use the security functions on the site.