Online holiday shopping in the workplace poses an IT security risk for employers, especially those with younger workers, according to a new report by the Information Systems Audit and Control Association.

Four out of every 10 Americans aged 18-24 are expected to spend up to five hours shopping online over the holiday season, according to the Rolling Meadows, Ill.-based IT trade group.

A recent survey of 973 employees nationwide found younger workers were the least concerned about workplace network security, the group reported. Roughly half said they paid more attention to the security of their home computers, while two thirds of employees over 25 said they worried about both home and office systems.

The survey found many employees don’t understand how to protect workplace computers. Twenty-two percent of respondents said they've clicked on e-mail links to an online retailer, and more than a quarter said they either don’t bother or don’t know how to check a site’s security.

In a separate survey, over half of the trade group's 3,100 members said they allow shopping at work, even though many haven't trained employees to guard against potential IT security threats.

“The fact that Millennials are planning to spend the equivalent of more than half a work day doing holiday shopping from their work computer, combined with their lack of concern for how secure their computer is, points to an urgent need for employee education,” Kent Anderson, a member of the group's Security Management Committee, said in a statement.