IT security and control firm Sophos has reminded computer users about the danger of internet scams following the arrest of ten people in Spain alleged to have defrauded victims via an email lottery scam.

The ten people, all Nigerian nationals, are suspected of making more than 19,000 Euros ($28,000) in three months by demanding payments from innocent internet users who believed they had won a lottery.

Police report that the emails sent by the suspects were sent from the Teatinos area of Malaga in Spain, by piggybacking on a neighbour's wi-fi internet connection without permission. Seven arrests were made in Malaga, and three more in Huelva province.

"If an email sounds too good to be true, it probably is. Emails scams like this arrive in the inboxes of many every day of the week, all around the world - and clearly some people are falling for them," said Graham Cluley, senior technology consultant for Sophos. "It sounds like the authorities were able to shut down this scam quite quickly before too many people were affected - but there are plenty more cybercriminals looking for ways to steal people's identities and rob their bank accounts."

Sophos experts note that Malaga is no stranger to Nigerian-run email scams. In 2005, 310 people were arrested in Malaga in what was said to be the biggest ever bust of a lottery scam gang. The arrests followed an investigation by the FBI and Spanish police into a scam run by Nigerian gangs.

Sophos believes that the police claims that the gang used an innocent party's internet connection to send their bogus lottery emails, underlines the importance of properly securing wireless access points at home.

"If you haven't properly secured your wi-fi connection at home you are effectively leaving the front door open for anybody close by to take advantage of it," continued Cluley. "Everyone running a wireless access point needs to learn how to stop unsavory characters from using it to spew out their spam messages, download illegal content, or steal information."

Tips for preventing strangers from stealing your Wi-Fi connection

1. Use encryption

Wi-Fi Protected Access (WPA and WPA2) is a stronger encryption system than WEP, and can be used to reduce the chances of hackers intercepting your communications.

2. Use a password

Choose a strong password that has to be used to access your wireless access point. Don't use the default password that came with your Wi-Fi equipment or a dictionary word that is easy to guess or crack. (You may wish to read our article on sensible password use for help with this).

3. Don't broadcast the name of your wireless network

The name of your wireless network, known as the SSID, should not be broadcast to passers-by. In addition, choose an obscure hard-to-guess SSID name to make life harder for hackers. SSIDs such as "home", "wireless" or "internet" are not good choices.

4. Use MAC address filtering

Wi-Fi routers and access points normally have the ability to prevent unknown wireless devices from connecting. This works by comparing the MAC address of the device trying to connect with a list held by the router. Unfortunately, this feature is normally turned off when the router is shipped because it requires some effort to set up properly. By enabling this feature, and only telling the router the MAC address of wireless devices in your household you can reduce the chances of strangers' computers piggybacking your internet connection.

Unfortunately it is possible for a determined hacker to clone MAC addresses, but this measure should still be taken to reduce the risks.

5. Restrict internet access to certain hours

Some wireless routers allow you to configure internet access to certain times of the day. For instance, if you know you will not need to access the internet from home between 9-5, Monday to Friday, then schedule your router to disable access between those hours.

6. Make sure your computers are properly secured

Make sure all of your computers are properly secured with up-to-date anti-virus, security patches, and client firewall software.

Sophos experts recommend that computer users be wary of all unsolicited emails, and protect their email gateways with a consolidated product to defend against spam, phishing, viruses and spyware.

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