McAfee is warning small and medium sized businesses against complacency when it comes to IT security.

One third of the companies surveyed by McAfee for its report entitled ‘Does Size Matter?' had been attacked at least four times during the past three years, it said.

But, worryingly, many companies affected – who lost a week or more as a result – failed to recognise that they were in fact worthy of attack by cybercriminals, and were a source of income for the unscrupulous. One in five UK companies affected has had to sacrifice a week before they could get up and running again, revealed the report.

Also, McAfee found that many smaller companies have just one hour a week to dedicate to IT security.

Darrell Rodenbaugh, McAfee's senior vice president of the mid-market segment said: ‘Just because a business is small, it doesn't mean it's immune to security threats.

‘For businesses of all sizes, viruses, hacker intrusions, spyware and spam can lead to lost or stolen data, computer downtime, decreased productivity, compliance issues, lost sales and even loss of reputation.'

He adds that most companies mistakenly believe that default IT security settings are sufficient when it comes to protecting themselves.

The report, which also contains advice on how smaller organisations can protect themselves, is available for free download on McAfee's website: