There are two types of precision agriculture systems – those that have been hacked, and those that will be. Connectivity and information flow are the two key enabling factors for successful operation of the digital farm. These elements also represent the most vulnerable aspects open to cyber-attack, with the aim of disrupting food production. The use of a principles-based framework to assess cyber-attack vulnerabilities in precision agriculture technology as well as in the environment to which it is applied can greatly mitigate the risk of cyber-attack. From this farmers can construct a precision agriculture system that is appropriately protected from cyber-attacks and matched to the complexity level of the technology without unnecessary cost. Future areas of research include analyses of cyber-attack consequences through modelling cyber-physical system vulnerabilities, detection design and security architecture.