The SYSTEM_OBJECT_INFORMATION structure (formally _SYSTEM_OBJECT_INFORMATION) is an irregularly recurring element in what a successful call to ZwQuerySystemInformation or NtQuerySystemInformation produces in its output buffer when given the information class SystemObjectInformation (0x11). The output begins with a SYSTEM_OBJECTTYPE_INFORMATION. There can be, and typically are, more of these throughout the buffer, but irregularly because each can be followed by any number of SYSTEM_OBJECT_INFORMATION structures. These too are irregularly spaced because although each is fixed in size, each is followed in turn by a variable-size Unicode string.

Documentation Status

The SYSTEM_OBJECT_INFORMATION structure is not documented.

Microsoft does publish the practical equivalent of a C-language definition as type information in symbol files—not for the kernel, where the structure is prepared, nor even for low-level user-mode DLLs that interpret the structure, but for a handful of higher-level DLLs that might ordinarily be thought very distant from any involvement with the structure. Perhaps only by oversight, but starting as long ago as Windows 8, Microsoft’s downloadable packages of public symbols have included a smattering of private symbol files and these continue to be available through the public symbol server. Precisely which DLLs have the type information varies between versions. COMBASE.DLL is among the more reliable nowadays. Disclosure in symbol files for URLMON.DLL stopped for the 1803 release of Windows 10 but is specially notable because of this DLL’s origins in Internet Explorer and thence for the strong suggestion that Microsoft’s programmers of Internet Explorer had access to more details of low-level Windows programming than Microsoft publishes for wider use (including by the programmers of competing web browsers).

Type information for the structure has also seeped out at the other end of the Windows timeline, though not in symbol files but in statically linked libraries: GDISRVL.LIB from the Device Driver Kit (DDK) for Windows NT 3.51; and SHELL32.LIB from the DDK for Windows NT 4.0.


The SYSTEM_OBJECT_INFORMATION is 0x30 or 0x50 bytes in 32-bit and 64-bit Windows, respectively.

Offset (x86) Offset (x64) Definition Versions
0x00 0x00
ULONG NextEntryOffset;
0x04 0x08
PVOID Object;
0x08 0x10
PVOID CreatorUniqueProcess;
0x0C 0x18
USHORT CreatorBackTraceIndex;
3.50 and higher
0x0C (3.10);
ULONG Flags;
3.10 only
3.50 and higher
0x10 0x1C
LONG PointerCount;
0x14 0x20
LONG HandleCount;
0x18 0x24
ULONG PagedPoolCharge;
0x1C 0x28
ULONG NonPagedPoolCharge;
0x20 0x30
PVOID ExclusiveProcessId;
0x24 0x38 unknown dword 3.10 only
PVOID SecurityDescriptor;
3.50 and higher
0x28 0x40