Why This Startup Raised $42.5 Million Before It Came Out Of Stealth

Illumio is a computer security startup with a product so radical, it raised $42.5 million before it even came out of stealth mode, and from a who's who of investors.

Its backers include Salesforce.com CEO Marc Benioff, Yahoo founder Jerry Yang, Box's CEO Aaron Levie, Andreessen Horowitz's Ben Horowitz, Joe Lonsdale, Matthew Ocko of Data Collective and Steve Herrod, an early VMware employee turned VC for General Catalyst Partners.

In fact, when we met Herrod in the summer, he called Illumio "one of the new wave of thinkers in how security should work."

Herrod was chomping at the bit to tell us more, but at that time, couldn't.

On Wednesday, Illumio officially opened for business with a tweet from Horowitz:

Illumio offers computer security designed for the cloud, where a nudie picture taken with your smartphone can wind up on some server somewhere in the cloud where a hacker can steal.

Illumio "creates a protective bubble that surrounds an application, moving with it whenever and wherever it runs - whether on bare-metal or virtualization in a private datacenter or in public clouds provided by Amazon, Google, or Microsoft," Herrod wrote on his blog Tuesday.

Founded by Andrew Rubin and PJ Kirner, as well as a number of former Cisco, VMware, and McAfee employees, Illumio's new technology - called Adaptive Security Platform - will foil those hackers, its backers say.

Another thing that makes Illumio different is that it works automatically. Illumio, it can see that something about the network has changed, and adapt its security accordingly.

"Some of our customers are very large and have millions of firewall rules. It was almost impossible to master all of that. But we're using computing to take care of it," Alan Cohen, Illumio's CTO told Business Insider.

Those customers include some of the most data-heavy companies, such as Morgan Stanley, Yahoo, and Creative Artists Agency. Cohen said Illumio has 25 customers now, and it's only going to grow because its technology is "actually very hard to build."

Perhaps, that explains why some of the most prominent investors are so excited about Illumio.