When IBM loosened its restrictions on the smart phones and tablets its employees could use for work, the company got a lesson in IT management of the kind it usually sells to clients.

In 2010, like many large companies in recent years, IBM adopted a "bring your own device" policy, meaning that employees who want to work outside the office don't have to use a smart phone provided by the company. Although IBM still gives BlackBerrys to about 40,000 of its 400,000 employees, 80,000 other workers now reach internal IBM networks using other smart phones and tablets, including ones they purchased for themselves.

The trend toward employee-owned devices isn't saving IBM any money, says Jeanette Horan, who is IBM's chief information officer and oversees all the company's internal use of IT. Instead, she says, it has created new challenges for her department of 5,000 people, because employees' devices are full of software that IBM doesn't control.

Horan says that when IBM surveyed several hundred employees using mobile devices, many were "blissfully unaware" of what popular apps could be security risks.