Mobile agent technology offers a new computing paradigm in which a program, in the form of a software agent, can suspend its execution in a host computer, transfer itself to another agent-enabled host in the network, and resume execution of the new host. As the sophistication of mobile software has increased with the time, so have the associated threats to security. This paper provides an overview of the range of threats facing the designers of mobile agent. The paper also identifies generic security objectives, and a range of measures for countering the identified threats.