Does the shared lib bug work on any suid program ?

[Bernd.Lehle () RUS Uni-Stuttgart DE (Bernd Lehle)]

Hi there,

after all the fuzz about the telnet/shared lib stuff somebody here came up
with something that might be even more interesting:

What woul hapen in the following case:

- Choose any suid program, that uses a library call, You know the name
- example: su calls crypt(3)
- take the library that contains crypt and delete crypt from it
- add a crypt function that does exec(sh)
- rebuild the shared library with the new cypt
- set the shared library path to Your home
- su

Right after the Password was typed in, You should have a root shell...

This game could be played with any suid program, where You know what routines
it calls.

Or am I missing something ?

I did not try this yet, because I don't know (yet) how to build shared
libraries ...

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