The world's largest maker of networking gear posted a message on its Web site more than a week after a portion of its Internetworking Operating System source code was illegally copied and posted on a Russian site.
Cisco said it was cooperating with the FBI and other law enforcement agencies investigating the theft. It referred questions about the investigation to the FBI, which did not immediately return a phone call seeking comment Friday.
"As a matter of policy, Cisco takes information security very seriously and continues to take active measures to protect its proprietary information as well as employee, customer and partner information," according to the statement, made public Thursday.
Cisco also said the pilfered code has been removed from the foreign Web site where it had been available for several days. The company said the theft "was not the result of a vulnerability in any product or service offered by Cisco."
It also said the company has no reason to believe the leak was the result of any malicious activity by an employee or contractor.
Analysts and experts say it's possible that the source code could be used by hackers to find and exploit vulnerabilities in the software. So far, no such hacks have been reported.
"It represents a risk to the company certainly with respect to potential reputation lost," said Dan Geer, chief scientist of Verdasys, an information security company.
San Jose-based Cisco is the world's leading maker of network routers and switches, the devices that carry and direct traffic over the Internet and other networks.
The software breach is the second time this year a prominent technology company has faced an embarrassing disclosure of its source code. In February, some pieces of Microsoft Corp.'s tightly guarded blueprints for some versions of Windows were circulating on the Internet.