• The deal is worth more than $500 million, according to one report.
• Security is a growth area for Microsoft.

Microsoft said Monday it has agreed to acquire RiskIQ, a cybersecurity start-up, for undisclosed terms.

The deal could help Microsoft expand its security business, which is growing faster than other segments. In January, Microsoft said it derived more than $10 billion in security revenue in the past 12 months, up more than 40% year over year.

RiskIQ's Illuminate software aggregates threats across a given organization's information technology footprint so security professionals can address the most critical ones. The system works across Microsoft's Azure cloud, and other clouds such as market-leading Amazon Web Services. It also works with on-premises infrastructure, Eric Doerr, vice president for cloud security at Microsoft, wrote in a blog post.

Microsoft has had to contend with security issues recently, including exploits of versions of its Exchange Server email and calendar software.

RiskIQ was established in 2009 and is based in San Francisco, with more than 200 employees, according to LinkedIn. Investors include Battery Ventures and MassMutual Ventures. RiskIQ competitors include publicly traded Mimecast.

Over the weekend Bloomberg reported, citing an unnamed source, that Microsoft would pay more than $500 million for RiskIQ.

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