Organisations spend large sums of money to ensure that they are protected against the risks associated with external threats. The perceived threats against organisations are well known, and the losses can be quantifiable. The perceived threat considered here is that associated with hackers. Much is known about hackers, their rationale, and their ethical views. However, it is harder to quantify what computer abuse is and what the associated losses are. This chapter focuses on hackers, computer abuse, and ethical issues.