People hired to demonstrate vulnerabilities in systems by
exploiting those vulnerabilities.
Complexity: These people are usually honest, but sometimes they are not. In
addition, they often fail to properly repair the systems they try to break
into, thus leaving residual vulnerabilities. Their skills vary widely, from
rank ametures using off-the-shelf software - to true experts with a high
degree of sophistocation. It is often hard to tell which is which unless you
are an expert.