Microsoft was monitoring hackers for weeks

Microsoft spokesman Rick Miller said Sunday that beginning Oct. 14 a hacker gained access to high-level secrets and was able to view blueprints, or source code, for Microsoft software being developed.

Originally, the Seattle-based software giant said an electronic intruder had access to source code for as long as five weeks. On Friday, when the company first confirmed the it, the duration was unclear, Miller said.

The company was alerted to the break-in by the creation of new accounts that give users access to parts of Microsoft's computer network.

"We start seeing these new accounts being created, but that could be an anomaly of the system," Miller said. "After a day or two, we realized it was someone hacking into the system."

On Oct. 26, that the company notified federal law enforcement, which is investigating. Miller said the company is confident the high-level access occurred only between Oct. 14 and Oct. 25.

"We realized the intrusion had grown to the level that warranted bringing in the FBI," Miller said. Miller said the activity did not corrupt or modify the code for the product, however the hacker could have accessed corporate e-mails and other confidential information.

If any attempts to download or transfer the source code were made, such activity was not recorded in Microsoft's logs, Miller said. He said it was unlikely source code files were copied because of their immense size.

But at least one security expert questioned Miller's assessment.

"It's impossible to say with absolute certainty that (source code) file has not been copied," according to Simon Perry, vice president of security solutions at Computer Associates International in Islandia, N.Y. "Over a 12 day period, it would be absolutely possible to take a copy of that."

Microsoft has refused to identify what program the source code was for, except to say it was a product years from release — not Windows or Office software.

Microsoft's source codes are the most coveted in the multibillion-dollar industry. With access to the software blueprints, competitors could write programs that undermine Microsoft — or use the data to identify vulnerabilities, making computer break-ins and virus-writing easier.

For instance, the 'Love Bug' virus that crippled computers around the globe in May exploited a security glitch in Microsoft's market-leading e-mail programs.

The hackers in this particular case used what is called a "Trojan horse," a program commonly sent as an e-mail attachment that looks normal but once inadvertently activated by the user can wreak havoc on a computer system.