RunSybil

RunSybil builds Sybil, an AI agent that runs penetration tests against software that is already deployed rather than reading source code.

It probes applications, APIs, cloud accounts and infrastructure the way an attacker would, chaining weaknesses together and testing authentication boundaries to reach sensitive data, including cross-tenant access, privilege escalation and IAM misconfigurations.

Testing reruns as new code ships, so it can stand in for periodic manual pentests, bug bounty work and parts of internal red teaming.

The company was founded in 2023 by Ari Herbert-Voss, OpenAI's first security research hire, and Vlad Ionescu, who led offensive security red teams at Meta. It names Cursor, Notion and Baseten among its customers.