Hackers going by the name Shadow Brokers said on Monday they will auction stolen surveillance tools they say were used by a cyber group linked to the U.S. National Security Agency.

To arouse interest in the auction, the hackers released samples of programs they said could break into popular firewall software made by companies including Cisco Systems Inc, Juniper Networks Inc and Fortinet Inc.

The companies did not respond to request for comment, nor did the NSA.