As enterprises strengthen defenses to prevent data loss from outside attack, their own workers' wide disregard of rules puts information at risk, a security company said Monday.

A poll of more than 300 American office workers released by McAfee revealed that while the majority -- 84% -- operate under company rules about how to treat sensitive information, 1 in 5 admitted to leaving confidential documents in a common printer output tray. A similar number said they sometimes lend portable devices used to store sensitive work documents to co-workers.

"Policy combined with technology that focuses on outside attacks alone clearly isn't enough to protect companies from the threat of data loss," said Vimal Solanki, McAfee's senior director of worldwide product marketing, in a statement. "The harsh reality is that sensitive corporate data can easily end up in the wrong hands -- deliberately or accidentally -- because of employee behavior."

In other survey findings, the poll noted that of the workers who said they transfer customer data out of the organization, 88% admitted to using e-mail for the move, with 23% of that group saying that they use even less-secure Web-based e-mail to transfer data out of office.

Nearly 4 out of every 10 workers polled said that they take up to 10 documents out of the office each week on a variety of portable devices: laptops (41%), USB flash drives (22%), and CDs (13%).

Also on Monday, McAfee announced Data Loss Prevention Host, a software agent-server software combination that lets data administrators deploy centrally managed policies to end-point systems to lock down and/or track all data leaving those clients via e-mail, IM, print, USB drives, CDs, and other avenues.