1. A method comprising: prior to execution of a computer-based training exercise, providing a virtual environment in which the computer-based training exercise is to be executed, wherein the virtual environment includes an attack system and a target system, and wherein providing the virtual environment comprises: receiving a model of a network topology of the target system, the network topology of the target system including one or more virtual network elements; selecting at least one source document that defines one or more rules for use by the target system; and configuring the target system based on the one or more rules defined by the at least one source document, wherein configuring the target system includes automatically instantiating one or more virtual machines of the target system that correspond to the one or more virtual network elements included in the network topology of the target system; and during execution of the computer-based training exercise, and responsive to a simulated attack initiated by the attack system against the one or more virtual machines of the target system, performing, by the one or more virtual machines of the target system, one or more corrective or preventive actions that are specified by a human trainee, wherein, responsive to the one or more corrective or preventive actions performed by the one or more virtual machines of the target system, the attack system responds by automatically generating dynamic response data that is sent from the attack system to the target system to initiate a change in the simulated attack against the one or more virtual machines of the target system.