Re: [Full-disclosure] Local suid files and buffer overflows
From: Fósforo (fosforo_at_gmail.com)
Date: Sun, 9 Oct 2005 13:41:37 -0300 To: firstname.lastname@example.org
try copying /bin/bash to /tmp/ directory, setting suid for all
2005/10/9, Joachim Schipper <email@example.com>:
> On Sun, Oct 09, 2005 at 01:17:39AM +0200, Werner Schalk wrote:
> > Hi,
> > first of all apologies for asking such a newbie question but I am trying
> > to learn how to exploit buffer overflows and therefore wrote a little
> > program to exploit. This little program has the following permissions:
> > $ ls -la test1
> > -rwsr-sr-x 1 root root 17164 Oct 8 01:25 test1
> > Now I exploited it using Aleph One's shellcode (see
> > http://shellcode.org/shellcode/linux/null-free/) but I won't get a SUID
> > shell afterwards (I know the exploit did work but I still have my normal
> > user privleges). Why? I have tried a different shellcode to write a file
> > and this file was root:root. Any ideas, hints, rtfm?
> > Thank you.
> > Best regards,
> > Werner.
> Try the following:
> # mount
> /dev/hdb2 on /home type ext3 (rw,nosuid,nodev)
> nosuid means that suid binaries lose their special properties here.
> See mount(8). As you just proved, it's not completely useless.
> As an additional exercise, bypass the nosuid mount option. Or just copy
> it somewhere without nosuid.
> (There are many, many other ways this behaviour could have happened, but
> this one sounds most likely...)
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