PicoCTF 2013 - overflow1

First overflow1 challenge from PicoCTF 2013. Old but (still) good for a practice. ;) Let's do it...

I started from the links found at github where you can find multiple copies of challenges from old (as well as some 'current') CTF competitions. One of the was overflow1.

At github I found source and binary:

I opened the target-file in gdb:

Breakpoint set to the end of the current listing of vuln() function:
 

Payload file ('1') was created as a simple: $ python -c 'print "A"*200'>1:

Checking new value(s):

We still need to decrement the value:

Better. ;] Checking without gdb:

See you next time!

Cheers