Palo Alto Networks, a provider of enterprise network security, on Monday scored $27 million in a third round.

The new round led by Lehman Brothers Venture Partners and return backers Globespan Capital Partners, Greylock Partners, and Sequoia Capital brings the total funding up to $54 million.

The new funds will be used to support the company’s rapid growth by further expanding sales, marketing, and customer service initiatives, the company announced in a press release.

Palo Alto Networks, based in Sunnyvale, California, not Palo Alto, offers next-generation firewalls to protect companies from threats that take advantage of infrastructure vulnerabilities.

The firewall company made headlines last week when Microsoft credited--in its Security Bulletin-- the startup’s Threat Research Team for discovering a total of five vulnerabilities in its system since last year.

Palo Alto Networks is a Red Herring North America 2008 finalist.