mips assembly display string using buffer overflow

Question

I am practicing buffer overflow and assembly coding. Right now I am able to find return address, and jump to anywhere inside the program itself. However, I want to do more than just jump to itself, I want to display some string that I sent to the program buffer (the string is not included in the program, but it's an input I sent with my exploit). Lets say I want to display "you are hacked!", how can I do that?

I understand to display something, I need to call prints() function inside the program itself, and assign the address value to $a0, which is the argument passing into prints() and prints() will print anything in that address out. However, my input string is not included in the program, I have no way to display my own message but only the data in program itself. How can I do that?

Why don't you put your string into the buffer you are overrunning? Are you limited in size of buffer? :D (pun intended) — Ped7g
– Ped7g, Commented Oct 31, 2016 at 16:33
thx! I was so tired that I didn't know solution is already there. I just found out the way to solve it! You clear my thoughts, thanks! — Tom Dawn
– Tom Dawn, Commented Oct 31, 2016 at 16:52

Tom Dawn · Accepted Answer · 2016-10-31 16:54:34Z

0

I had the answer just a step away, I did put my hack message into the buffer. I was wrongly putting the string in $a0, however what I really should do is to put the memory address of the string into $a0. As soon as I did that, my hack message displayed.

answered Oct 31, 2016 at 16:54

Tom Dawn

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