Re: Re: Buffer Overflow Help

[Matt Woodyard <woodyard () sdgky com>]

Is this not related to wide-character unices? I seem to recall that when
I ran through this tutorial having a unicode enabled glibc messed with
it pretty bad.

On Mon, 2002-08-12 at 13:55, Ali Saifullah Khan wrote:
> Yes, you're right chris.
> the distance calculated also depends on the gcc version used to 
> produce the assembley code viewed to calculate the distance on the 
> stack moved.
>
> versions of gcc later than ...91 seem to be showing different 
> activity.....like skipping 8 bytes instead of 4 for the same 
> purpose if i may recall.
>
> please do check up on that last statement....i maybe wrong about 
> the # of bytes skipped.
>
> Thankyou.
>
> On Wed, 31 Jul 2002 Chris Hall wrote :
> >    There was a thread on the vuln-dev list about this very same 
> > issue. I believe the distance calculated depends
> > on the enviornment , ( ie: 8,16,32,64 bit systems )
> >
> >
> > http://online.securityfocus.com/archive/82/266675/2002-03-30/2002-04-05/1
> >
> >
> > -- Chris
> >
> > Leonard Leblanc wrote:
> >
> > > Hello All,
> > >
> > > I am trying to experience buffer overflows first hand. I have 
> > > glanced at a
> > > number of articles and have decided to focus on "Smashing the 
> > > Stack for Fun
> > > and Profit" from Phrack Issue 49. I am trying out the examples 
> > > from the text
> > > and when I get to example 3 (which is the first real overflow 
> > > example) it
> > > doesn't quite work and I'm having a little trouble figuring it 
> > > out.
> > >
> > > The following example should bypass the "x=1" statement and 
> > > print the
> > > original value of "x" which is 0 (zero). Here's the code.
> > >
> > > -=-=-=-=-=-=-=-=-=-=-=-=-=
> > > void function(int a, int b, int c) {
> > >  char buffer1[5];
> > >  char buffer2[10];
> > >  int *ret;
> > >
> > >  ret = buffer1 + 12;
> > >  (*ret) += 8;
> > > }
> > >
> > > void main() {
> > >  int x;
> > >
> > >  x=0;
> > >  function(1,2,3);
> > >  x=1;
> > >  printf("%d\n",x);
> > > }
> > > -=-=-=-=-=-=-=-=-=-=-=-=
> > >
> > > When I compile and execute this code it displays one and exits. 
> > > I have tryed
> > > this on RedHat 7.3 and Debian 2.2r6, both giving me the same 
> > > result. Does
> > > anyone have any insight into why this wouldn't work? After 
> > > looking into the
> > > assembly behind it, I think it has something to do with the 
> > > "word size", but
> > > can't seem to find any information as to what the "word size" is 
> > > in Debian
> > > or RedHat.
> > >
> > > Any and All comments/suggestions are more than welcome. Also if 
> > > anyone knows
> > > of some other good text files/documents that talk about buffer 
> > > overflows I
> > > would be happy to receive links.
> > >
> > > Leonard Leblanc
> >
> >
> > >
> >
> >
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>
> Ali Saifullah Khan,
> Project Administrator,
> ConnPROBE Intrusion Detection System.
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-- 
Matt Woodyard (0x8659BAA7)
CISSP
SDG - Security Analyst
My other computer is in Russia.
8592637344x133
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