Facebook has been hit by the biggest wave of spam in its history, according to a security firm which registered five different attacks leaving unsolicited messages on users' walls in the last 24 hours.
"Facebook is vulnerable to spam by design," says Urban Schrott of antivirus company ESET. "Facebook users trust the messages they see on their friends' walls, and have no fear of clicking them."
Spammers are increasingly turning to targeted attacks on social networks, where they can use social engineering techniques to exploit users' natural curiosity towards links that are posted on their Facebook walls - many of which lead to dodgy web pages designed to capture credict card details or other identity information, or even download malicious software onto unsuspecting users' computers.
"2010 was the first year [email] spam volumes went down," Cisco security chief Tom Gillis said at the DEMO IT conference in Palm Desert, California on Monday. "Does that mean spam is less of a problem? No."
ESET's Schott agrees: "Since there are more than 500m Facebook users, Facebook spam became a multimillion-dollar business for cyber criminals. A good and up-to-date antivirus software can protect you from downloading malware, but it cannot protect your Facebook wall. If you click on a spam message, it could infect your computer and it spreads to your friends.
"Antivirus software cannot protect users from Facebook spam, since the spam is working inside Facebook. The only defence against it is user awareness and thinking before clicking."