Your boss is asking each engineer from all departments to come up with the one or two sources of network threats and attacks you consider the most critical and why. He wants you to be able to fit your thoughts on an index card. He does not care if the same problem is addressed from several points of view or if you address a very specific "threat of the day" or one from the past that could come back. You are also asked to have an opinion about the potential risks of such threats and attacks.