Continuous attack and defense is becoming a security business model. Horizon3 just raised $250M in Series E money, at a valuation above $2B, to push that model further with autonomous penetration testing. NightDragon and New Enterprise Associates co-led; Acrew Capital, Sapphire Ventures and SAIC were among seven new participants.
Its NodeZero tool launches offensive probes across internal networks, cloud setups and Kubernetes deployments, then attempts to link separate weaknesses into full attack chains. A credential leak in one system may lead to administrative access in another, and the tool documents each step as proof.
NodeZero also surfaces problems that are not software bugs at all, such as weak passwords, exposed credentials and poor network segmentation. Its tests can pivot from on-premises systems into AWS, Azure and Microsoft 365 when a viable path exists.
AI plays a bounded role. Deterministic, prevalidated logic carries out the exploits; generative models help pick high-value targets, interpret business impact and write summaries. Horizon3 says generative AI never authors or executes attacks, keeping production runs constrained and reproducible.
The company reports roughly 310,000 completed tests for more than 7,000 organizations, including four Fortune 10 firms, with annual recurring revenue up 120% year over year. The new capital funds entry into Singapore and Australia plus automated remediation that verifies fixes by rerunning the tests.
