DarkCTF 2020: Rev/strings

Rev/strings

363 points

Description:Just manipulation of couple of strings....
Note: Enclose the final output inside darkCTF{} File

Solution

I used the ghidra to do the initial analysis. Looks like binary takes the input (do nothing with it;)), then calculate some string (I assumed it's a flag) and exit.

Let's try to debug...

gdb ./strings
break _exit
run

Then dumped the memory before program exit.

Ok, let’s examine the memory dump…

Oh?! What’s that? Is it a flag? Bingo! ;-)

darkCTF{wah_howdu_found_me}