Windows kernel internals

Security, Compliance and Identity.Mainframe programming.KiInvalidOpcodeFaultShadow fffffd5a nt! This allows for the possibility of using either direct procedure calls or interprocess communication IPC to communicate between modules, and hence for the potential location of modules in different address spaces for example in either kernel space or server processes.Hari Pulapaka on Feb 21 PM.These lower level drivers directly control hardware and do not rely on any other drivers.Latest Comments.Namespaces Article Talk.Microsoft Business.Microsoft Localization.Windows kernel internals Inc.
Architecture of Windows NT – Wikipedia

Windows Kernel Internals II Overview University of Tokyo – Products 72 Special Topics 41 Video Hub Hari Pulapaka on Mar 11 AM.Kernel mode in Windows NT has full access to the hardware and system resources of the computer.Education Microsoft in education Office for students Office for schools Deals for students and parents Microsoft Azure in education.Thanks to spotless contributionwe can also dump the whole SSDT list togethr with the symbols names.

Hotpatching on Windows.Hotpatching is an impact-less update technology which has been keeping the Azure fleet up-to-date for years with zero im Developer Guidance for Hardware-enforced Stack Protection.Windows 10 implementation details of Hardware-enforced Stack Protection, which takes advantage of the latest chipset sec Introducing Kernel Data Protection, a new security technology for preventing data corruption.

Kernel Data Protection KDP is a new technology that prevents data corruption attacks by protecting parts of the Window Hari Pulapaka on Apr 06 PM.

Understanding Hardware-enforced Stack Protection.Hari Pulapaka on Mar 24 AM.In this post, we will DTrace on Windows — 20H1 updates.Hari Pulapaka on Jan 27 AM.DTrace on Windows.Hari Pulapaka on Mar 11 AM.Windows Sandbox – Config Files.Hari Pulapaka on Feb 21 PM.Windows Sandbox.Hari Pulapaka on Dec 18 PM.Windows Sandbox is a new lightweight desktop environment tailored for safely running applications in isolation.Learn mo Mitigating Spectre variant 2 with Retpoline on Windows.

Read about how the Windows Kernel team adapted retpoline for Windows to deliver a high-performance mitigation for Spectr One Windows Kernel.Hari Pulapaka on Oct 17 PM.In this blog post, I will talk about the evolution of the core pieces of the Windows kernel that allows it to transparen Welcome to Windows Kernel Team Blog.

Hari Pulapaka on Sep 27 PM.Latest Comments.According to 0patch’s FAQ, they don’t patch the kernel for the specific reason you mention How to identify User mode or Kernel mode are being used?

Do that mean if we enable shadow stack, user mode and kernel mode are both being used? John, are you confirming that it fails BOTH if you try to run a.For performance reasons, however, in version 4.

Applications that run on NT are written to one of the OS personalities usually the Windows API , and not to the native NT API for which documentation is not publicly available with the exception of routines used in device driver development.An OS personality is implemented via a set of user-mode DLLs see Dynamic-link library , which are mapped into application processes’ address spaces as required, together with an emulation subsystem server process as described previously.

Applications access system services by calling into the OS personality DLLs mapped into their address spaces, which in turn call into the NT run-time library ntdll.The NT run-time library services these requests by trapping into kernel mode to either call kernel-mode Executive routines or make Local Procedure Calls LPCs to the appropriate user-mode subsystem server processes, which in turn use the NT API to communicate with application processes, the kernel-mode subsystems and each other.

Windows NT uses kernel-mode device drivers to enable it to interact with hardware devices.Each of the drivers has well defined system routines and internal routines that it exports to the rest of the operating system.Kernel mode drivers exist in three levels: highest level drivers, intermediate drivers and low level drivers.Intermediate drivers consist of function drivers—or main driver for a device—that are optionally sandwiched between lower and higher level filter drivers.

The function driver then relies on a bus driver—or a driver that services a bus controller, adapter, or bridge—which can have an optional bus filter driver that sits between itself and the function driver.Intermediate drivers rely on the lowest level drivers to function.The lowest level drivers are either legacy Windows NT device drivers that control a device directly or can be a PnP hardware bus.

These lower level drivers directly control hardware and do not rely on any other drivers.The Windows NT hardware abstraction layer , or HAL, is a layer between the physical hardware of the computer and the rest of the operating system.

It was designed to hide differences in hardware and provide a consistent platform on which the kernel is run.However, despite its purpose and designated place within the architecture, the HAL isn’t a layer that sits entirely below the kernel, the way the kernel sits below the Executive: All known HAL implementations depend in some measure on the kernel, or even the Executive.In practice, this means that kernel and HAL variants come in matching sets that are specifically constructed to work together.

In particular hardware abstraction does not involve abstracting the instruction set, which generally falls under the wider concept of portability.Abstracting the instruction set, when necessary such as for handling the several revisions to the x86 instruction set, or emulating a missing math coprocessor , is performed by the kernel, or via hardware virtualization.

From Wikipedia, the free encyclopedia.This article is about the Windows NT kernel.For the Windows NT kernel image, see ntoskrnl.For the Windows 9x kernel, see Architecture of Windows 9x.Overview of the architecture of the Microsoft Windows NT line of operating systems.Microsoft Windows Professional Resource Kit.Retrieved O’Reilly and Associates, Inc.

ISBN Windows NT Workstation documentation.Microsoft TechNet.Archived from the original on 15 December Archived from the original on 10 February Russinovich; David A.Solomon; Alex Ionescu.Windows Internals, Fifth Edition.Microsoft Press.Archived from the original on 13 January Microsoft Corporation.Finnel, Lynn Russinovich, Mark October Windows IT Pro.

Solomon, David ; Russinovich, Mark E.Inside Microsoft Windows Third ed.Archived from the original on Russinovich, Mark ; Solomon, David Microsoft Windows Internals 4th ed.Schreiber, Sven B.Undocumented Windows Secrets.Addison-Wesley Longman.Siyan, Kanajit S.Windows Professional Reference.

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Windows Kernel Internals Windows Server Architecture Kernel.Hardware Abstraction Layer (HAL).Hardware interfaces (read/write port, timers.This course takes a deep dive into the internals of the Windows kernel from a security perspective with an emphasis on internal algorithms, data structures.Kernel mode in Windows NT has full access to the hardware and system resources of the computer.The Windows NT kernel is a hybrid.

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  3. Programs and subsystems in user mode are limited in terms of what system resources they have access to, while the kernel mode has unrestricted access to the system memory and external devices.
  4. Here is also an overview of how some process and thread structures are interlinked.
  5. The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to.
Windows 10 Kernel Mitigations and Exploitation w/ Jaime Geiger \u0026 Stephen Sims – SANS HackFest Summit, time: 53:29

Windows Kernel Internals Blog

How to identify User mode or Kernel mode are being used? One Windows Kernel.

Architecture of Windows NT – properties

  • Why Choose Wintrac.
  • The Hardware Abstraction Layer HAL is a layer of code that isolates the kernel, the device drivers, and the rest of the Windows executive from platform-specific hardware.
  • The security subsystem deals with security tokens, grants or denies access to user accounts based on resource permissions, handles login requests and initiates login authentication, and determines which system resources need to be audited by Windows NT.
  • This section focuses on these different execution environments and discusses the restrictions that apply to each one of them.
  • If we inspect the content of the ServiceTable we can verify that contains offset of actual kernel routines.
  • Archived from the original on 10 February
  • Windows Kernel Internals.
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For x64, the three values we are after are:.In x64 Windows systems, the values are:.The next instruction, mov qword ptr gs:[h],rsp saves the user-land stack pointer into the.Continuing reading the Syscall routine, the GSh value is saved at RSP, containing the x64 page directory PML4 Quoting the Fortinet article about the next instruction bt dword ptr gs:[h],1 mov cr3,rsp.A flag […] will be checked, and if swapping is needed then the base of PML4 corresponding to the kernel address space will be moved into CR3.

At this point the kernel stack is finally accessible and everything works normally.We note that swapping may not always be needed as it may have already happened previously for example, interrupt while servicing system calls.One subtle thing to notice is that after the new PML4 has been moved into CR3 the address space is switched instantaneously, and the very next instruction fetch happens on the new address space private to the kernel.The main kernel files can be summed as follows:.

Image: lsass.KeKernelStackSize : [Type: int].KiDivideErrorFaultShadow fffffd5a nt! KiBreakpointTrapShadow fffffd5a nt! KiOverflowTrapShadow fffffd5a nt! KiBoundFaultShadow fffffd5a nt! KiInvalidOpcodeFaultShadow fffffd5a nt! KiInvalidTssFaultShadow 0b: fffffd5a nt!

KiStackFaultShadow 0d: fffffd5a nt! KiGeneralProtectionFaultShadow 0e: fffffd5a nt! KiPageFaultShadow 0f: fffffd5b2f8 nt! KiFloatingErrorFaultShadow fffffd5a nt! KiAlignmentFaultShadow fffffd5a nt! This mechanism was designed to support applications written for many different types of operating systems.None of the environment subsystems can directly access hardware; access to hardware functions is done by calling into kernel mode routines.

The Win32 environment subsystem can run bit Windows applications.It contains the console as well as text window support, shutdown and hard-error handling for all other environment subsystems.Win16 programs, however, run in a Win16 VDM.Each program, by default, runs in the same process, thus using the same address space, and the Win16 VDM gives each program its own thread on which to run.

The Win32 environment subsystem process csrss.It handles input events such as from the keyboard and mouse , then passes messages to the applications that need to receive this input.

Each application is responsible for drawing or refreshing its own windows and menus, in response to these messages.The security subsystem deals with security tokens, grants or denies access to user accounts based on resource permissions, handles login requests and initiates login authentication, and determines which system resources need to be audited by Windows NT.Windows NT kernel mode has full access to the hardware and system resources of the computer and runs code in a protected memory area.

The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to; user mode processes must ask the kernel mode to perform such operations on their behalf.While the x86 architecture supports four different privilege levels numbered 0 to 3 , only the two extreme privilege levels are used.

These two levels are often referred to as “ring 3” and “ring 0”, respectively.Code running in kernel mode includes: the executive, which is itself made up of many modules that do specific tasks; the kernel , which provides low-level services used by the Executive; the Hardware Abstraction Layer HAL ; and kernel drivers.

Grouped together, the components can be called Executive services internal name Ex.System Services internal name Nt , i.The term “service” in this context generally refers to a callable routine, or set of callable routines.

This is distinct from the concept of a “service process”, which is a user mode component somewhat analogous to a daemon in Unix-like operating systems.The kernel sits between the HAL and the Executive and provides multiprocessor synchronization, thread and interrupt scheduling and dispatching, and trap handling and exception dispatching; it is also responsible for initializing device drivers at bootup that are necessary to get the operating system up and running.

That is, the kernel performs almost all the tasks of a traditional microkernel ; the strict distinction between Executive and Kernel is the most prominent remnant of the original microkernel design, and historical design documentation consistently refers to the kernel component as “the microkernel”.

The kernel often interfaces with the process manager.The Windows NT design includes many of the same objectives as Mach , the archetypal microkernel system, one of the most important being its structure as a collection of modules that communicate via well-known interfaces, with a small microkernel limited to core functions such as first-level interrupt handling, thread scheduling and synchronization primitives.

This allows for the possibility of using either direct procedure calls or interprocess communication IPC to communicate between modules, and hence for the potential location of modules in different address spaces for example in either kernel space or server processes.Other design goals shared with Mach included support for diverse architectures, a kernel with abstractions general enough to allow multiple operating system personalities to be implemented on top of it and an object-oriented organisation.

On versions of NT prior to 4.For performance reasons, however, in version 4.Applications that run on NT are written to one of the OS personalities usually the Windows API , and not to the native NT API for which documentation is not publicly available with the exception of routines used in device driver development.An OS personality is implemented via a set of user-mode DLLs see Dynamic-link library , which are mapped into application processes’ address spaces as required, together with an emulation subsystem server process as described previously.

Applications access system services by calling into the OS personality DLLs mapped into their address spaces, which in turn call into the NT run-time library ntdll.The NT run-time library services these requests by trapping into kernel mode to either call kernel-mode Executive routines or make Local Procedure Calls LPCs to the appropriate user-mode subsystem server processes, which in turn use the NT API to communicate with application processes, the kernel-mode subsystems and each other.

Windows NT uses kernel-mode device drivers to enable it to interact with hardware devices.Each of the drivers has well defined system routines and internal routines that it exports to the rest of the operating system.

Kernel mode drivers exist in three levels: highest level drivers, intermediate drivers and low level drivers.Intermediate drivers consist of function drivers—or main driver for a device—that are optionally sandwiched between lower and higher level filter drivers.The function driver then relies on a bus driver—or a driver that services a bus controller, adapter, or bridge—which can have an optional bus filter driver that sits between itself and the function driver.

Intermediate drivers rely on the lowest level drivers to function.The lowest level drivers are either legacy Windows NT device drivers that control a device directly or can be a PnP hardware bus.These lower level drivers directly control hardware and do not rely on any other drivers.

The Windows NT hardware abstraction layer , or HAL, is a layer between the physical hardware of the computer and the rest of the operating system.It was designed to hide differences in hardware and provide a consistent platform on which the kernel is run.However, despite its purpose and designated place within the architecture, the HAL isn’t a layer that sits entirely below the kernel, the way the kernel sits below the Executive: All known HAL implementations depend in some measure on the kernel, or even the Executive.

In practice, this means that kernel and HAL variants come in matching sets that are specifically constructed to work together.In particular hardware abstraction does not involve abstracting the instruction set, which generally falls under the wider concept of portability.

Abstracting the instruction set, when necessary such as for handling the several revisions to the x86 instruction set, or emulating a missing math coprocessor , is performed by the kernel, or via hardware virtualization.From Wikipedia, the free encyclopedia.This article is about the Windows NT kernel.For the Windows NT kernel image, see ntoskrnl.

For the Windows 9x kernel, see Architecture of Windows 9x.Overview of the architecture of the Microsoft Windows NT line of operating systems.Microsoft Windows Professional Resource Kit.

: None of the environment subsystems can directly access hardware; access to hardware functions is done by calling into kernel mode routines.

The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to; user mode processes must ask the kernel mode to perform such operations on their behalf.Each of the drivers has well defined system routines and internal routines that it exports to the rest of the operating system.

  • BTW, that shortcut ends up running WindowsSandbox
  • It can be reached at the fixed address 0x7ffe from user-mode, while from kernel is located at fffff on x64 architectures.
  • Hotpatching is an impact-less update technology which has been keeping the Azure fleet up-to-date for years with zero im
  • In particular hardware abstraction does not involve abstracting the instruction set, which generally falls under the wider concept of portability.
  • Understanding Hardware-enforced Stack Protection.

Microsoft Localization.Microsoft PnP.Healthcare and Life Sciences.Internet of Things IoT.Enabling Remote Work.Small and Medium Business.Humans of IT.Green Tech.MVP Award Program.Video Hub Azure.Microsoft Business.Microsoft Enterprise.Browse All Community Hubs.Turn on suggestions.Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for.Show only Search instead for.Did you mean:.Sign In.Windows Kernel Internals Blog.Hotpatching on Windows.Hotpatching is an impact-less update technology which has been keeping the Azure fleet up-to-date for years with zero im Developer Guidance for Hardware-enforced Stack Protection.Windows 10 implementation details of Hardware-enforced Stack Protection, which takes advantage of the latest chipset sec Introducing Kernel Data Protection, a new security technology for preventing data corruption.

Kernel Data Protection KDP is a new technology that prevents data corruption attacks by protecting parts of the Window Hari Pulapaka on Apr 06 PM.Understanding Hardware-enforced Stack Protection.Hari Pulapaka on Mar 24 AM.In this post, we will DTrace on Windows — 20H1 updates.Hari Pulapaka on Jan 27 AM.Here is a summary of where are placed and how are interconnected together.Here is also an overview of how some process and thread structures are interlinked.

A thread is the entity actually running code.Last, the ObjectTable which is ultimately pointing to the Handle Table.We can fetch some more details about threads, as usual viakd, by querying the target process with more details 0 2 :.Amount of kernel information shared with user-mode, in order to avoid multiple transition to kernel.It can be reached at the fixed address 0x7ffe from user-mode, while from kernel is located at fffff on x64 architectures.

Other system specific values that can be used for fingerprinting purpose.An SST is a Windows lookup struct table.If we inspect the content of the ServiceTable we can verify that contains offset of actual kernel routines.Thanks to spotless contribution , we can also dump the whole SSDT list togethr with the symbols names.

Once we hit the userland side of the function, we can inspect its privileges and PL level, which 3 as expected.We can also double check in the Service Table that the correct offset will point to the actual kernel system call implementation.

For x64, the three values we are after are:.In x64 Windows systems, the values are:.The next instruction, mov qword ptr gs:[h],rsp saves the user-land stack pointer into the.Continuing reading the Syscall routine, the GSh value is saved at RSP, containing the x64 page directory PML4 Quoting the Fortinet article about the next instruction bt dword ptr gs:[h],1 mov cr3,rsp.

A flag […] will be checked, and if swapping is needed then the base of PML4 corresponding to the kernel address space will be moved into CR3.At this point the kernel stack is finally accessible and everything works normally.We note that swapping may not always be needed as it may have already happened previously for example, interrupt while servicing system calls.

One subtle thing to notice is that after the new PML4 has been moved into CR3 the address space is switched instantaneously, and the very next instruction fetch happens on the new address space private to the kernel.

The main kernel files can be summed as follows:.

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Show only Search instead for.Did you mean:.Sign In.Windows Kernel Internals Blog.Hotpatching on Windows.Hotpatching is an impact-less update technology which has been keeping the Azure fleet up-to-date for years with zero im Developer Guidance for Hardware-enforced Stack Protection.

Windows 10 implementation details of Hardware-enforced Stack Protection, which takes advantage of the latest chipset sec Introducing Kernel Data Protection, a new security technology for preventing data corruption.Kernel Data Protection KDP is a new technology that prevents data corruption attacks by protecting parts of the Window Hari Pulapaka on Apr 06 PM.Security, Compliance and Identity.Microsoft Edge Insider.Azure Databases.

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