Based in Reston, Va., iDefense supplies information on network security threats and software vulnerabilities to financial-services firms, government agencies, and others. The firm has more than 200 researchers in 30 countries.
VeriSign executives said the acquisition will expand its managed security services offerings by offering customers added capabilities to protect their networks.
VeriSign plans to retain iDefense employees, who will continue to sell the iDefense portfolio of intelligence services. John Watters, CEO of iDefense, will lead VeriSign's iDefense research team.
Early last year, VeriSign acquired managed security services firm Guardent.
The deal represents continued consolidation in the security market. Last month, Computer Associates bought Tiny Software.