Cybersecurity heavyweight Imperva Inc. today announced that it’s buying Distil Networks Inc., a venture-backed startup that helps companies keep bots away from their websites and applications.

The terms of the transaction were not disclosed. The deal marks the fifth startup buyout that the security industry has seen in the past week, a streak that speaks to both the strength of the market and the central role strategic acquisitions play in established players’ growth strategies.

Arlington, Virginia-based Distil has developed a cloud service for defending online services against malicious bot traffic. It acts as a filter that blocks illegitimate requests from reaching websites, mobile apps and the application programming interfaces a company provides for outside developers.

Distil distinguishes bots from human visitors by assessing hundreds of small technical details about each web request. The service checks the browser from which a request originated, the user’s device, their location and even what mouse movements they make while interacting with a service. Distil then assembles these data points into a unique “fingerprint” that the startup says can used to identify a bot even if it’s actively trying to avoid detection.

Imperva plans to incorporate the service into its application delivery platform, which is used by companies to protect their services against cyberattacks. The offering blocks distributed denial-of-service campaigns, attempts to exploit software vulnerabilities and a variety of other common online threats.

“While Imperva already protects our customers from malicious bots and automated attacks, integrating Distil Networks into our platform will significantly enhance our capabilities,” Imperva Chief Technology Officer Kunal Anand wrote in a blog post. “Our goal is to provide a single-pane-of-glass view of bots and other attacks for customers.”

The purchase of Distil is Imperva’s first acquisition since it was taken private by Thoma Bravo LLC last year in a $2.1 billion buyout. Three months before that deal, the security provider shelled out $140 million for Prevoty Inc., a startup whose technology enables applications to autonomously defend themselves against certain types of attacks.

Photo: Imperva