Re: Why SUID Binary exploit does not yield root shell?

[Shaun Clowes <shaun () securereality com au>]

Hi Kryptik,

> I've managed to find a buffer overflow and exploit it to exeve a /bin/sh
> using my payload shellcode. However, whenever I run my exploit, I do get a
> shell but just that it is an ordinary shell under my account (as id would
> indicate).

It's quite likely that the program in question is dropping privileges 
before the buffer overflow occurs. To determine if that's the case try 
modifying your shellcode to perform a trap (INT3, 0xcc) and run the exploit 
under the debugger. When the shellcode executes the program should stop. 
Then you can just look in /proc/<pid>/status, the ids on the "Uid:" line 
represent the real, effective, saved and filesystem user ids respectively. 
If these are all no longer root, there is nothing you can do to restore 
privileges.

One other way to determine if the program is dropping privileges would be 
to run strace on the binary and see if set(re)uid has been called before 
the overflow point.

Cheers,
Shaun