Toward Risk Thresholds for AI-Enabled Cyber Threats: Enhancing Decision-Making Under Uncertainty with Bayesian Networks

Abstract

Artificial intelligence (AI) is increasingly being used to augment and automate cyber operations, altering the scale, speed, and accessibility of malicious activity. These shifts raise urgent questions about when AI systems introduce unacceptable or intolerable cyber risk, and how risk thresholds should be identified before harms materialize at scale. In recent years, industry, government, and civil society actors have begun to articulate such thresholds for advanced AI systems, with the goal of signaling when models meaningfully amplify cyber threats, for example, by automating multi-stage intrusions, enabling zero-day discovery, or lowering the expertise required for sophisticated attacks. However, current approaches to determine these thresholds remain fragmented and limited. Many thresholds rely solely on capability benchmarks or narrow threat scenarios, and are weakly connected to empirical evidence. This paper proposes a structured approach to developing and evaluating AI cyber risk thresholds that is probabilistic, evidence-based, and operationalizable. In this paper we make three core contributions that build on our prior work that highlights the limitations of relying solely on capability assessments. First, we analyze existing industry cyber thresholds and identify common threshold elements as well as recurring methodological shortcomings. Second, we propose the use of Bayesian networks as a tool for modeling AI-enabled cyber risk, enabling the integration of heterogeneous evidence, explicit representation of uncertainty, and continuous updating as new information emerges. Third, we illustrate this approach through a focused case study on AI-augmented phishing, demonstrating how qualitative threat insights can be decomposed into measurable variables and recombined into structured risk estimates that better capture how AI changes attacker behavior and outcomes.