Ari Herbert-Voss

Ari Herbert-Voss is co-founder and CEO of RunSybil, an offensive security company with hubs in San Francisco, California, and New York City. He started it in 2023 with Vlad Ionescu, who earlier led offensive security red teams at Meta. Its AI agent, Sybil, tests applications and infrastructure the way a human hacker would.

From Utah to OpenAI

Herbert-Voss grew up in Utah and was drawn to the online hacker scene in middle and high school, then stepped away after friends “started getting arrested,” he told Fortune. He was working on a machine learning PhD at Harvard University when OpenAI released GPT-2. “Once OpenAI dropped GPT-2, I said wow, this changes everything about the economics of what it would take to run a cyber campaign,” he said.

He sent hacking demos to OpenAI's leaders, left Harvard, and joined OpenAI in 2019 as its first security research hire. He spent about three years there working on GPT-3, Codex, and API monitoring.

Attack surfaces that keep growing

By 2022 he could see how fast offensive cyber capabilities would grow once strong language models were widely available, and he left to start RunSybil as a research project. His view, described in a TBPN interview, is that AI coding tools produce code faster than human security teams can review it, so testing has to speed up too. He wants customers to treat testing “not as a project, but as a permanent capability embedded in how they build,” he told Fortune.