RunSybil, an AI cybersecurity startup that uses autonomous agents to hack company software and find security weaknesses, has raised $40 million in seed funding led by Khosla Ventures. The round, announced on March 18, represents one of the largest seed raises in the cybersecurity space this year.
From OpenAI and Meta to Offensive Security
The company was co-founded in 2023 by Ari Herbert-Voss, OpenAI's first security researcher, and Vlad Ionescu, who previously led the offensive security red team at Meta. Their combined experience at two of the most prominent AI and technology companies informs RunSybil's core thesis: that AI agents can perform penetration testing more continuously and comprehensively than human security teams.
RunSybil's AI agent, Sybil, conducts autonomous penetration tests against live applications — finding, exploiting, and documenting real security vulnerabilities without human intervention. Unlike traditional automated vulnerability scanners that check for known patterns, Sybil is designed to reason about application logic and discover novel attack vectors.
Investor Lineup Signals Confidence
The investor roster reads as a who's who of AI and security leadership. Beyond lead investor Khosla Ventures, the round includes S32, the Anthology Fund (a joint effort from Anthropic and Menlo Ventures), Conviction, and Elad Gil. Angel investors include Nikesh Arora, Amit Agarwal, Jeff Dean, and other current and former leaders from OpenAI, Palo Alto Networks, Stripe, and Google.
The company did not disclose its valuation.
Why It Matters
Enterprise security teams face a well-documented talent shortage. Qualified penetration testers are expensive and scarce, and most organizations can only afford periodic security assessments — often quarterly or annually. RunSybil's pitch is that its AI agent can run continuous offensive testing, catching vulnerabilities as they are introduced rather than months later.
The funding will be used to deepen RunSybil's engineering investment, expand its security research capabilities, and accelerate go-to-market efforts.
A Growing Category
RunSybil enters a rapidly expanding market for AI-powered security tools. As enterprises deploy more AI agents across their operations, the attack surface grows correspondingly — creating demand for security solutions that can keep pace. The company's approach of using AI to attack software, rather than just defend it, reflects a broader shift toward proactive security postures in an era of increasingly autonomous systems.
