Before we go on

The next step would be to look for what I call "easy money". Before we can go into the details of this, there are some points to understand. There are some major differences between auditing a network and hacking into a network. Let us look at the analogy of a house. On the one hand you have the true blue blood burglar - the objective is getting into the house with whatever means possible. The burglar looks for the easiest and safest way to get into the house and he does not care about all the other means. On the other hand the security officer - it is his job to tell the client of every single little hole in the house. The difference between the security officer and the burglar is that when the security officer finds the front door wide open he notes it, and looks for other problems, whereas the burglar find the front door open and walks straight in, ignoring the other holes. In the cyber world it works the same. So, hiring a hacker (in the criminal sense of the world) to audit a system is a bit worrisome. The hacker will surely help you to find a weakness in your defense, but the idea of an IT security audit is not this - the idea is to find all the holes and fix them. Once you and your security advisor is confident that all holes are closed you might want to hire a hacker (or penetration specialist) to try to penetrate the network. The bottom line - doing penetration testing and doing a comprehensive security assessment of a network is not nearly the same thing.
This document had come to the point where I have to decide which route we are going to follow - the view of the hacker or the view of the IT security assessment officer. Choosing either one of the options I cannot continue with Citibank as an example unless I want to land in potentially serious trouble. The rest of the document - with the focus on either hacking or assessing will thus be looking at actual client networks - networks we every right to penetrate. The techniques can be implemented at Citibank as well - in the exact same way, but I simply cannot do it right here and now as Citibank is not my client (unfortunately).