Mkdir exploit for PDP-11 doesn't work

[Jonathan S]

Tim Newsham is right that there is an overflow present, but his exploit
doesn't work (for me - it may work fine on his PDP-11 or emu). A bus
error is what happens, which is a good sign that the return address needs
to be changed. It sucks that there aren't very many tools in UnixV7,
including text editors.

Here's the log of me executing the code he posted (I'll probably have it
fixed so it works in 5 minutes, with any luck):

$ pwd
/tmp
$ ./id
ruid=7 rgid=3
$ ./mkdir_exp
mkdir: cannot access
A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A.A. A.AeVB.Be
x2
B.!
C.!.D.a.!.!.; I.I.I.I.I./bin/shaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ~/.
Bus error - core dumped
$ ./id
ruid=7 rgid=3
$


Sincerely,

Jonathan Stuart, CISSP
js@gti.net (personal)

[Denis Solaro]

On Wed, 9 Jun 2004 18:36:31 -0400 (EDT)
Jonathan S <js@apollo.gti.net> wrote:

> Tim Newsham is right that there is an overflow present, but his exploit
> doesn't work (for me - it may work fine on his PDP-11 or emu). A bus
> error is what happens, which is a good sign that the return address needs
> to be changed. It sucks that there aren't very many tools in UnixV7,
> including text editors.
>
> Here's the log of me executing the code he posted (I'll probably have it
> fixed so it works in 5 minutes, with any luck):

This could be induced by a bad grounding of the main console. It happened to me
a few times when I've touched on of the panels. You get a slight jolt and then
a few error messages when the hard drive unit is activated. This is slightly
annoying but doesn't lead to a real security problem for the PDP-11.
In my case Apache crashes, but I didn't find any proofs of any files tempered
with.