London's corporates are "spilling data" onto the streets, according to the results of an RSA Security-sponsored study.

The security specialist's latest wireless security survey of London, an annual event conducted by driving round the centre of London with a laptop and wireless network detection software, found that "more than a third of businesses with wireless networks are open to abuse from hackers and criminals in the street or a neighbouring building."

RSA reckons the research indicates that wireless security in London has deteriorated in the past year; last year researchers found that only 15 per cent of wireless networks were not secured. It also claimed that there was "an explosion" in the number of wireless networks.

The survey also said that many businesses had failed to take basic security precautions such as reconfiguring their default network settings. In London, 26 per cent of access points still used default settings. According to RSA, this means that wireless network access points were still broadcasting potentially valuable information, which could be sabotaged or used to launch subsequent attacks.

Tim Pickard, area VP of international marketing for RSA Security said: "Like a thief trying all the door handles in the car park hoping to get lucky, London's business centres are comparable to a hackers' playground. With over a one-in-three chance of finding an unsecured wireless business network the odds are in the hacker's favour. Our research shows that corporate wireless networks in London are growing at an annual rate of 62 per cent and 36 per cent of these businesses remain unprotected from attack."

Report author Phil Cracknell of netSurity, said: "These figures are another stark warning to unsecured businesses to get their act together. 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 they will access and what they will do when they are there?"

Pickard said: "These results reinforce why it is crucial to increase 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 businesses 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."

In addition to the business security issues, researchers also found an increase in public access wireless hotspots - 12 per cent of all wireless network access points in London fell into this category.

However, the reality is that the problem is not as serious as RSA would like to believe. For example, experience suggests that very few if any large companies have switched their entire enterprise networks over to wireless. The open networks could also well be trials and temporary setups for specific projects, which minimises the risk.

And there remain plenty of small businesses in the heart of the UK's capital. Likely to be the most prolific users of wireless networks, their data is unlikely to be of as much interest as, for example, that of a major bank.

Alternatively, of course, they could be set up by individual large company employees without the technical savvy to secure them.