How to....

["Greg" <security-basics () pchandyman com au>]

....really shoot your XP machine in the foot, so to speak.

Pick any program shortcut that is pinned to your start menu. If you don't 
have any, find any old program shortcut (or make one) then pin it to your 
start menu. Now go find some other shortcut to a completely different 
program and open it's properties. Copy the full path info from that one and 
past it into the path info in the properties for that other shortcut that is 
pinned to the start menu and click OK to make it stick. Now carefully look 
at that icon. It hasn't changed. Now click on it. The icon now starts that 
other program instead of the one it looks like it is SUPPOSED to start.

Now while all that is simple "so what?" to most of you, think of this - I 
deal in a lot of low level security stuff that is below the radar of a lot 
of you but if an icon that is frequently used in the list of commonly used 
programs or those pinned to the start menu can be so easily changed to start 
some other program yet not look like it was tampered with at all, why 
couldn't the next Trojan include code to do this? Eg, place a Trojan on the 
C drive, copy the full path info into the "Windows Update" icon on your 
start menu (for example) where it runs that Trojan instead. That Trojan may 
do what it is designed to do and also do the actual starting of Windows 
Update after that.

What stops a local user or a Trojan doing this in a normal XP installation 
that hasn't been changed and all runs at admin levels as so many businesses 
do?

Greg.