"Businesses—watch out—you need to control the power within your companies. One of your biggest security threats exists behind your firewall. Survey results revealed that 88 percent of exiting employees will use their IT-know-how to take your company data with them, including privileged password lists that give them access to hundreds, even thousands of sensitive data files," said Adam Bosnian, vice president of products, strategy and sales at Cyber-Ark.

And it's wise to remember that allowing your former employee to leave with dignity can save you some headaches down the road. See Management: How to Fire People. If you're the employee, you might want to read 18 Signs You're About to Get Fired.

The survey of 300 IT security professionals was conducted at Infosecurity 2008.

"If laid off tomorrow, [they] would take valuable and sensitive company information with them. The target information includes the CEO's passwords, the customer database, R&D plans, financial reports, M&A plans, and most importantly the company's list of privileged passwords, Cyber-Ark said in a statement. "Only 12 percent revealed that they would plan to leave empty handed."

The survey also found that a third of IT staff use their privileged rights and administrative passwords to snoop for confidential files, including personal and salary information, e-mails, and merger and acquisition plans.

Still think your important files are secure?