The explosion of wireless networks is leaving global businesses wide open to 'drive-by hacking' and other security risks, experts have warned.

According to research released today, more than a third of businesses worldwide with wireless networks are open to abuse from hackers and criminals in the street or a neighbouring building.

The study, commissioned by RSA Security, estimated that wireless networks in Europe's financial capitals alone are growing at an annual rate of 66 per cent, and more than a third of businesses remain unprotected from this type of attack.

"For a potential hacker it is almost a case of walking down the street and trying all the doors until one opens. It is almost inevitable that one will," said John Worrall, vice president of worldwide marketing at RSA Security.

The research was based on studies in the business centres of New York, San Francisco, London and Frankfurt.

Some 38 per cent of businesses in New York, 35 per cent in San Francisco, 36 per cent in London and 34 per cent in Frankfurt were at risk from drive-by hacking.

The study also revealed that many businesses had failed to take even basic security precautions such as reconfiguring default network settings.

This means that wireless network access points could still be broadcasting valuable information that could be used by potential hackers and assisting them in launching an attack.

In London 26 per cent of access points still had default settings, 30 per cent in Frankfurt, 31 per cent in New York and 28 per cent in San Francisco.

In addition to the business security issues, researchers also found an explosion in public access wireless hotspots; 12 per cent of all wireless network access points in London fell into this category, compared with 24 per cent in Frankfurt, 21 per cent in New York and 12 per cent in San Francisco.

"These figures are another stark warning to unsecured businesses to get their act together," said Phil Cracknell, chief technology officer at NetSurity and the author of the research.

"The rapid rise of wireless public access hotspots runs in parallel to the increased risk to businesses that operate wireless networks with little or no security.

"Accidental or intentional connection to a corporate network can bring with it a series of security issues including loss of confidential data and installation of malicious code.

"Fuelled by the availability and abundance of hotspots, mobile users now expect to find, and know how to use, a wireless network. The question is whose network will they access, and what will they do when they are there?"

Worrall added: "These results reinforce why it is crucial to increase the understanding of security risks in the wired and wireless world.

"This is the fourth year of our survey and the situation shows no sign of improvement. While it is clear that business are benefiting from the flexibility and ease-of-use of wireless technology, they must also ensure that the right security steps are taken to protect against exploitation."

The researchers used a laptop computer and free software available from the internet to pick up information from company wireless networks simply by driving around the streets.