Time for more pain.
I like this one. It'll be different than the last few, and might involve a bit of a brain stretch for those not familiar with exploit techniques that differ from the norm. It'll hurt. There's a bit of basic reversing, but that's not the problem.
"This is very important" --Olney
"If I were your husband I would take it." -- Winston Churchill, hon VRT
All the AWBO exercises are available at http://www.snort.org/vrt/tools/awbo.html