Malicious behavior arises spontaneously in many complex systems. Whenever agents can adapt their behavior to achieve competitive advantage, especially by subverting the operating rules of the system itself, cheating and other destructive behaviors often emerge. For example, viruses and cancer exploit the reproductive mechanisms of host cells to replicate and spread; bullies use intimidation to exert power, violating social norms; investors are duped by numerous schemes to manipulate financial markets; and cybercriminals exploit software vulnerabilities, eroding trust in networked systems. Studying the general principles that complex systems use to manage such threats can suggest techniques for tackling the problem of cyber security. The talk will highlight research that studies how ideas from biological defense systems have been applied to solve cybersecurity problems. It will also discuss how using the tools of complexity science to understand today's technological networks and their linkages to human behavior, social norms, and economic incentives can help us address the global scale of today's many cybersecurity problems.