Network security provider Sourcefire on Wednesday announced the acquisition of cloud-based anti-malware start-up Immunent for $21 million. The acquisition expands Sourcefire's portfolio by adding a cloud platform for the delivery of malware protection and extending the company's existing intrusion detection and prevention technologies into the cloud. Immunent, founded in July 2008, serves more than 750,000 users in 192 countries. Sourcefire will retain all full-time Immunent employees, including founders Oliver Friedrichs, Alfred Huger and Adam O'Donnell. – AM