What must bad actors know to create computer viruses?

To create computer viruses, a comprehensive understanding of program code is essential. This knowledge enables bad actors to write and implement malicious software that can exploit vulnerabilities in systems. Proficiency in programming languages allows them to design viruses that can replicate, spread, and execute harmful actions, like corrupting files or stealing data.

While insights into network architecture can help in understanding how viruses propagate across networks, and knowledge of social engineering can be useful for tricking users into enabling the virus, these do not directly involve the technical creation of a virus. Similarly, familiarity with data encryption methods may help protect against or circumvent security measures but is not a fundamental requirement for crafting the virus itself. Therefore, expertise in program code stands as the foundational skill required for writing and deploying malware, highlighting its significance in the context of this question.