American Airlines pilots did a few simple searches on a company intranet recently, and they came up with some interesting results -- including personal information on their colleagues and top company executives.

Personal information -- including Social Security numbers of more than 300 pilots and other employees at American Airlines, such as the chief executive -- was exposed on a company Website, according to the pilots union, the Allied Pilots Association.

American says only pilots and union officials saw the information on a password-protected internal site, according to a wire report.

Union officials say that by searching the site for "AA" and "medical" they collected roughly 200 results on the intranet -- including a 2002 document with personal information on 315 current and former pilots and about 50 others, including airline CEO Gerard Arpey and his predecessor, Don Carty.

Union President Ralph Hunter says he called Mark Burdette, the company's vice president of employee relations, to report the breach, according the Associated Press.

"I told him what his Social Security number was and where I got it," Hunter says. "He agreed with me that we had a big problem." American disabled the site's search function.

The incident raises some questions about the security of corporate intranets, many of which were built long before phrases such as "data leak prevention" and "insider attacks" became popular.

"The American Airlines situation is much more common than people think," says Eric Ogren, president of the Ogren Group, a security consultancy. "There is so much legacy data out there waiting for someone to stumble over. In some cases, IT doesn't even know that this data -- created before the days of data leakage and disclosure laws -- is at risk."

Robert Hansen, CEO of SecTheory LLC (a.k.a. RSnake), concurs. "The lion's share of compromises come from people with internal access to systems beyond their job descriptions." Several recent studies agree. (See Deep Threat and Study Highlights Insider Threats.)

The American Airlines incident is not the only recent breach to arise from simple misuse of a corporate intranet. On Friday, a manager at the Royal Bank of Scotland admitted to stealing approximately $50,000 after "borrowing" a colleague's internal network password and using it to systematically steal from a customer's mortgage account.

Many enterprises have conducted intranet security studies in the past, but most of them were focused on preventing outsiders from accessing the internal networks, experts say. But in many cases, a user who is authorized to log onto the intranet can use it to roam across data that goes well beyond his job responsibilities.

"A great example of this is secretaries, who often have keys to offices, passwords, access to email and calendars, etc.," Hansen says. "When you have underpaid and/or disgruntled people mixed with confidential information that falls outside of what their job requires, you have a dangerous situation."

— Tim Wilson, Site Editor, Dark Reading