Social networking sites, MySpace, Facebook and Bebo, and have climbed in popularity recently. They allow users to keep in contact with their friends and meet new ones, but they can also expose them to viruses, spyware and other online dangers. As the use of Web 2.0 applications, like wikis, blogs and social networking sites increases, they attract the attention of cyber criminals. Many of the people who use these sites are relatively new to the Internet and they can lack experience in dealing with online threats.

The threats described in this article have now been countered by site owners, but new ones will appear in future as attackers develop their techniques in response to improved security. The interactive nature of social networking sites allows them to spread threats very quickly, making them attractive targets. Many of these threats exploit the fact that people trust their friends, without realizing that it is important to treat electronic communications with care, no matter who they seem to be from. As with other aspects of Internet use, threats can be split into two categories: behavior-based and technology-based. Threats Posed by Behavior Behavior-based threats exist because users are not careful enough about the personal information they share online and make themselves vulnerable to phishing attacks and identity theft.

Users can publish information about their friends, their likes and dislikes, their jobs and hobbies, totally oblivious to the fact that that this information is eagerly sought by identity thieves as it can help them improve their credibility. Research carried out by IT security company Sophos on a random sample of Facebook users showed that 41% were prepared to divulge personal information like email address, date of birth and phone number to a complete stranger. The research involved creating a fictitious Facebook profile for a green plastic frog named Freddi and sending out 200 friend requests to randomly-chosen users throughout the world. 87 of the users contacted responded and 82 of them supplied personal information, including email addressed, date of birth, details about their education or workplace, address and phone number, as well as photos of friends and family and information about spouses, likes and dislikes and hobbies. In 2007 Internet Safety website Get Safe Online found that a quarter of UK social networking users had posted confidential personal information, such as their address or phone number on their social networking profiles.

13% of them had posted information or photos of other people online without their knowledge. This figure increased to a worrying 27% among users aged 18-24. Phishing isn't the only threat to be found on social networking websites. Eleven students at a high school near Toronto were suspended for posting comments about their principal on Facebook after the school imposed a ban on electronic devices and implemented a uniform policy. A school spokesman described the comments as vulgar and profane and claimed that they amounted to amounted to cyber-bullying. Several stories have claimed that young girls have been raped by older men who first met them via MySpace or Facebook, but none of these stories appear to have been conclusively proved.

However, it remains a major problem that social networking sites can offer an opportunity for men to meet young girls in an unsupervised environment, something which should be of great concern to parents. Threats Based on Technology Social networking sites can also be a source of technology-based threats. They allow millions of users to post content, so it's fairly inevitable that some of these will be malicious persons attempting to post viruses or spyware.

Early in 2008, more than three million Facebook users were infected with spyware in less than four days. A Facebook widget named "Secret Crush" or "My Admirer", reportedly downloaded by one and a half million users, claimed to tell users who had a secret crush on them, but actually tricked them into downloading the well-known Zango spyware. It spread by prompting users to forward the widget to five friends. Anti-virus vendor Symantec has claimed that vulnerabilities which could be used by hackers to snatch control of Windows PCs have been found in ActiveX controls offered to users by both Facebook and MySpace for uploading images to their pages via Internet Explorer (IE). The insecure controls are based on an ActiveX control named Image Uploader, produced by Aurigma Inc. Towards the end of 2005, 19-year old Samy Kamkar wrote a worm that infected more than a million MYSpace users and caused the site to shut down.

The Samy worm added a million friends to his profile within a few hours, adding the string "but most of all, Samy is my hero" to each of their profiles. Kamkar was later sentenced to three years probation and made to perform 90 days of community service. In January 2008 a 17-gigabyte file containing more than half a million pictures obtained from private MySpace profiles appeared on BitTorrent, a well-known peer-to-peer file sharing service. This is biggest privacy breach to date on a social networking site.

It was made possible because a security vulnerability, first reported in Autumn 2007, allowed hackers to access the photo galleries of some MySpace users who had set their profiles to private. This is the default setting for users aged under 16. This attack allowed pedophiles and voyeurs to target vulnerable 14- and 15-year-old users. In December 2007 users of Google's Orkut application based in Brazil were attacked by a worm that attempted to hijack their computers and steal their bank account details. The worm spread via booby-trapped links on the personal page of Orkut users and infected further users when they read messages from friends who had already been exposed.

This loophole was closed quickly, but another worm, called Scrapkut, appeared on Orkut early in 2008. It seemed harmless at first, but it was soon discovered that it could intercept login sessions at several Brazilian banking Web sites and replace components with a fake authentication prompt which could capture the users' logon credentials. YouTube has also been used indirectly to infect sites with malware. Many Internet users have received spam messages asking them to click on an attached YouTube video clip. The link actually takes them to a fake YouTube sight where they are told that they must install Adobe Flash Player to play the video.

Clicking the supplied download link causes a file called install_flash_player.exe. This is the same name as the real Flash installer, but it actually installs a Trojan known as Trojan-Dropper.

W32/Agent. Fighting Back We've considered some of the dangers that can be found on social networking sites, but what steps can you take to protect yourself against them? Fortunately, most of the technoology-based attacks can be prevented by the usual software defenses, ie: anti-virus software will protect you against viruses, Trojans and worms, anti-spyware programs will protect you against spyware and adware. A good-quality firewall will protect you against hackers and Internet safety suites will protect you against a variety of threats. Behavior-based attacks, which rely on persuading users to behave in an unsafe manner, are more difficult to deal with as they can only be countered by a change in user behavior. The Get Safe Online website provides a number of guidelines for networking safely, including the following: Don't allow peer pressure to push you into doing something you're uncomfortable with. Avoid posting information that can identify you, such as telephone or mobile numbers, photos of your home, workplace or school, your address, date of birth or full name.

Avoid including personal information in your username, eg: use laughing_boy33, rather than jim_brown. Set up a throwaway email account (eg: Hotmail or Yahoo) that doesn't resemble your real name and use that to register and receive mail from the site. Use a robust password with eight or more characters.

Avoid making comments or publishing photos which could embarrass you later. Use the privacy features on the site to control access to your profile. Be on the lookout for phishing scams. If you make sure that your software defenses are strong and up-to-date and you follow the above guidelines you should be able to enjoy social networking without problems.

If you have young children you should ensure that they are not allowed access to the Internet in an unsupervised environment. It's much better if the computer is in a family area, such as a lounge or dining room, rather than hidden away in a bedroom. Even with older children you should try to keep an eye on their Facebook or MySpace profiles and watch out for any changes in behavior which may suggest that they are encountering online problems.

Ted Hastings has many years of experience of IT and education. He has written a textbook on Internet Safety Skills and writes a popular blog entitled Surf Safely.