SCTF 2016 rev1 Writeup

rev1, 20 points, reversing

With this challenge being completed 572 times I think it is okay to go ahead and get a jump start on posting this write up. rev1 was a simple reversing problem for the sctf 2016 event. I am unsure if the event plans to host the files after it is complete but you can find a copy here.

I started by firing up gdb and disassembling main

Then look at <+68> as you can see we are comparing %eax and 0x5b74. So lets set a breakpoint at this address.

Now that we have a breakpoint at our compare lets run the program. You can type in whatever you want for the input and press enter, we are now at the breakpoint.

At this point lets set the value of $eax to 0x5b74 and continue running.

Woohoo! We got our flag!