A "security black hole" can be created through an employee's decision to use a virtual desktop, with an IT department's defences unable to keep track of any problems, it has been said.

The increasing popularity of virtualisation is presenting an increase in risk to both businesses and personal computer users, allowing people to use unauthorised applications such as file-sharing tools, according to Richard Jacobs of Sophos.

He asserted that this end-user action was reversing the benefits of the money-saving virtualisation option, with the technology becoming increasingly adopted by companies hoping to overcome their tightened IT budgets during the current economic climate.

Unmanaged workspaces such as virtual desktops, he added, could mean that applications may go without updates and viruses could find ways onto the network through unprotected peer-to-peer applications.

Mr Jacobs continued: "In fact, uncontrolled and unmanaged virtual computers could lead to potentially disastrous consequences, including corporate identity theft, financial losses and embarrassing headlines."

Graham Titterington of Ovum told ZDNet this week of the future threat of hackers accessing a computer through virtual desktops, adding that companies must take action now.

A recent Connect survey found that the two major concerns about outsourcing services like IT support were loss of control (56 per cent) and budget over-runs (43 per cent).