After updating a batch of Windows updates, it seems the ntdll.dll version got bumped from 6.1.7601.188869 (modified 25/5/15) to 6.1.7601.18933 (modified 15/07/2015).

Since then, !peb, !teb, !address and probably others have ceased to work for me because the _PEB and _TEB debug symbols are missing (same with _LDR_DATA_TABLE_ENTRY).

I couldn't find any reference online for it, but perhaps my google-fu is just weak.

2 Answers 2


From my cross-site answer:

You could assume that the types in ntdll have not changed so much. This would allow you to take an older version of wntdll.pdb and the new version of ntdll.dll and apply ChkMatch -m to it. This will copy the timestamp and checksum from the DLL to the PDB. After you did that (in an empty folder), replace the existing wntdll.pdb in your symbols directory with the hacked one.

WinDbg walkthrough (with output shortened to relevant things). I am using the latest version of wntdll.pdb I could find on my PC.

0:005> dt nt!_PEB
***                                                                   ***
***    Either you specified an unqualified symbol, or your debugger   ***
***    Type referenced: nt!_PEB                                       ***
***                                                                   ***
Symbol nt!_PEB not found.

0:005> lm m ntdll
start    end        module name
773f0000 77570000   ntdll      (pdb symbols)          e:\debug\symbols\wntdll.pdb\FA9C48F9C11D4E0894B8970DECD92C972\wntdll.pdb

0:005> .shell cmd /c copy C:\Windows\SysWOW64\ntdll.dll e:\debug\temp\ntdllhack\ntdll.dll
        1 file(s) copied.

0:005> .shell cmd /c copy "E:\Windows SDk\8.0\Debuggers\x86\sym\wntdll.pdb\B081677DFC724CC4AC53992627BEEA242\wntdll.pdb" e:\debug\temp\ntdllhack\wntdll.pdb
        1 file(s) copied.

0:005> .shell cmd /c E:\debug\temp\ntdllhack\chkmatch.exe -m E:\debug\temp\ntdllhack\ntdll.dll E:\debug\temp\ntdllhack\wntdll.pdb
Executable: E:\debug\temp\ntdllhack\ntdll.dll 
Debug info file: E:\debug\temp\ntdllhack\wntdll.pdb 

TimeDateStamp: 55a69e20 
Debug info: 2 ( CodeView ) 
TimeStamp: 55a68c18  Characteristics: 0  MajorVer: 0  MinorVer: 0 
Size: 35  RVA: 000e63e0  FileOffset: 000d67e0  
CodeView format: RSDS 
Signature: {fa9c48f9-c11d-4e08-94b8-970decd92c97}  Age: 2  
PdbFile: wntdll.pdb 
Debug info: 10 ( Unknown ) 
TimeStamp: 55a68c18  Characteristics: 0  MajorVer: 565  MinorVer: 6526 
Size: 4  RVA: 000e63dc  FileOffset: 000d67dc  

Debug information file: 
Format: PDB 7.00 
Signature: {b081677d-fc72-4cc4-ac53-992627beea24}  Age: 4 

Writing to the debug information file... 
Result: Success.

0:005> .shell cmd /c copy E:\debug\temp\ntdllhack\wntdll.pdb E:\debug\symbols\wntdll.pdb\FA9C48F9C11D4E0894B8970DECD92C972\wntdll.pdb
        1 file(s) copied.

0:005> .reload
Reloading current modules

0:005> dt nt!_PEB
   +0x000 InheritedAddressSpace : UChar
   +0x001 ReadImageFileExecOptions : UChar

0:005> !heap -s
LFH Key                   : 0x219ab08b
Termination on corruption : DISABLED
  Heap     Flags   Reserv  Commit  Virt   Free  List   UCR  Virt  Lock  Fast 
                    (k)     (k)    (k)     (k) length      blocks cont. heap 
Virtual block: 00920000 - 00920000 (size 00000000)
Virtual block: 02c60000 - 02c60000 (size 00000000)
Virtual block: 02e10000 - 02e10000 (size 00000000)

Note: using ChkMatch like this has the benefit that you do not need to turn on .symopt- 100, since that option would affect all PDB files, and you would not find potential other symbol issues. If you don't mind using .symopt, you could simply copy an old wntdll.PDB over the new one.


18933 builds have applied various security updates and the symbols on the symbol server are mangled. This is why WinDbg cannot perform those commands or list those structures for you.

If this is a debug machine, I would recommend reverting these updates temporarily.

  • 1
    It's the host machine actually, which I'd rather keep updated. Is there any information about this somewhere?
    – BarCo
    Aug 20, 2015 at 7:46

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