Rogue computer experts have tampered with America Online's business and customer information files, creating a security breach that could affect the accounts of subscribers to the giant on-line service.
A spokeswoman with the on-line service confirmed that the company has a security problem but would not disclose details of recent problems out of concern that any information could be used by hackers against the company's computer network.
But sources associated with the company said that the hackers appeared to have obtained access to a wide variety of files, including the personal files of Steve Case, the company's president and chief executive. America Online's spokeswoman would not confirm or deny that report.
In response, however, the on-line service has asked its staff to change their computer passwords. This week, the company will begin asking all of its 3 million members to periodically change their passwords for protection. A user of an on-line service must type a short password in order to read personal electronic mail or buy products. America Online also has recently installed new security software to stay a step ahead of the intruders.
The most recent incident, which came to light over the weekend when unpaid leaders of America Online forums were told to change their passwords, raises questions about whether an on-line service should alert members every time there is a potential security breach.
The security breach has been a subject of discussion among members of America Online's volunteer force, who are concerned about their own security and distressed with the on-line service for not informing all AOL members.
In the past several months, the company's service has been repeatedly attacked by a hacker program called AOHell. The recent attacks have involved AOHell, said Pam McGraw, an America Online spokeswoman.
The alleged break-ins come at a time when the service, based in Vienna, Va., is growing rapidly in a competitive market with new entrants. In the past 12 months, America Online has tripled its membership.