You'd think by now that any business aware of the danger of electronic attacks would have protected its systems accordingly, but apparently not. Software giant Microsoft has discovered that 65 percent of SME (small and medium-size enterprises) in the UK still have no form of intrusion detection system and 15 percent don't even have basic firewalls installed.

With an average security 'incident' costing SMEs an estimated £30,000, Microsoft is today warning companies to be on their guard for attacks over the traditionally busy period of April Fool's Day.

"April Fool's Day is a notorious time for hoax email viruses to be circulated," said Mike Pryke-Smith, medium business marketing manager at Microsoft. "But the threat posed by a genuine virus or hacker is not a joke — it's all too real.

"Businesses need to be aware there are simple steps and precautions they can take to deter security breaches," he added.

A number of concerned businesses have set up the eSecurity4Britain group, a non-profit organisation with the goal of raising awareness about "the associated threats of operating online".

The group's website enables visitors to attend live online events and discussion groups with experts to learn about such issues as implementing security policies, risk management, virus protection and defending against hackers.

"Dealing with online security is often a task that does not receive the priority it deserves," agrees Gerard Liston of SmallBizUK. "Even though safeguards are often highly affordable and easy to implement, many small firms operate their systems with fingers crossed."

Microsoft has released a free security toolkit for SMEs, which contains system upgrades and provides information identifying areas companies need to address.

A recent DTI survey revealed 44 percent of UK businesses had fallen victim to an IT security breach in the last year.