Cyberattacks are inevitable and widespread. Existing scholarship on cyberespionage and cyberwar is undermined by its futile obsession with preventing attacks. This Article draws on research in normal accident theory and complex system design to argue that successful attacks are unavoidable. Cybersecurity must focus on mitigating breaches rather than preventing them. First, this Article analyzes cybersecurity’s market failures and information asymmetries. It argues that these economic and structural factors necessitate greater regulation, particularly given the abject failures of alternative approaches. Second, this Article divides cyberthreats into two categories: known and unknown. To reduce the impact of known threats with identified fixes, the federal government should combine funding and legal mandates to push firms to redesign their computer systems. Redesign should follow two principles: disaggregation—dispersing data across many locations—and heterogeneity—running those disaggregated components on variegated software and hardware. For unknown threats—“zero-day attacks”—regulation should seek to increase the government’s access to markets for these exploits. Regulation cannot exorcise the ghost in the network, but it can contain the damage it causes.