Carrying out an application security assessment for a Visual Basic application

Hi all,

I need to do a security assessment of an application that is written
in Visual Basic. I am not too sure of the version. It is probably
version 6. The back end is Oracle.

What do I look at? I will ve able to get access to the source code. I
used to code in VB quite some time back so I should be able to
understand what is happening. However, from the application security
point of view, I need to know what to check.

Any one any pointers?
Pranav