How to use Google to find confidential informations

[Vincent GAILLOT <vgaillot () telecom insa-lyon fr>]

Hi, I am a french student and I heard recently about the capacity of google to 
deal with documents from Word, Excel or Powerpoint.
Intested in that fact, I decided to experiment some words and expression 
(with ") to look for (sorry if my english is not perfect..) and I found some 
combos that give enormous results.
In google, if you type things like :

1)"Index of /admin"
2)"Index of /password"
3)"Index of /mail"
4)"Index of /" +banques +filetype:xls (for france...)
5)"Index of /" +passwd
6)"Index of /" password.txt

And you can continue as long as your imaginatio is active.
For example of my results, I saw great informations from the central banks of 
Luxemboug and Switzerland, could admin a SQL server, ...

So, I don't know if it is a great technical bug, but I know about hacking and 
security (I would like to be a security consultant later..) (and I am looking 
for a training in security in a foreign country like US or England...) and even 
if we don't get root access immediatly, it is a great step for social 
engineering and spying.

I hope you will answer me very soon.
I love your web site !!!