Security startup Threat Stack announced today that it snagged a $15.3 million investment led by Scale Venture Partners. Through the deal, Scale partner Ariel Tseitlin will join the startup’s board.

Threat Stack says it helps enterprises “to scale with confidence by identifying and verifying insider threats, external attacks and data loss in real-time.”

The series B funding round will help Threat Stack double its personnel to “further enhance product capabilities and user experience,” the Boston-based startup said.

Threat Stack will also use the capital to open new Boston headquarters later this year.

To date, Threat Stack has raised at least $26 million. Previous investors, including Accomplice and .406 Ventures, also joined this latest round.