Windows kernel internals

Without getting into too many internal details about waits and the thread pool, this function essentially creates an event with the callback function EtwpNotificationThread and then calls NtTraceControl with an Operation value of 27 — an undocumented and unknown value.Solitaire Collection.Latest Activity.I found a tutorial that setup a config file that opened the do Grouped together, the components can be called Executive services internal name Ex.Microsoft Enterprise.Healthcare and Life Sciences.Then, in Windows kernel internalsimmediately after a notification is added to the notification queue for the process, this event is signaled: The event being signaled makes the EtwpNotificationCallback get called, since it was registered to wait on this event, so it is, in a way, an ETW notification callback that is being notified whenever the process receives an ETW notification.This makes you wonder what similar Windows kernel internals might exist in other pieces of ancient code that even Microsoft forgot about? Browse All Community Hubs.Windows Driver Model WDM exists in the intermediate layer and was mainly designed to be binary and source compatible between Windows 98 and Windows Microsoft Corporation.The Windows NT kernel is a hybrid kernel ; the architecture comprises a simple kernelhardware abstraction layer HALdrivers, and a range of services collectively named Executivewhich all exist in kernel mode.Video Hub Azure.Kernel Data Protection KDP is a new technology that prevents data corruption attacks by protecting parts of the Window Learn mo In case you want to see the three lines of code that trigger this bug, you can find them here.It handles input events such as from the keyboard and mousethen passes messages to the applications that need to receive this input.Then, in EtwpQueueNotificationimmediately after a notification is added to the notification queue for the process, this event is signaled:.The Windows NT hardware abstraction layeror HAL, is a layer between the physical hardware of the computer and the rest of the operating system.
Windows Kernel Internals Process Architecture

Exploiting a “Simple” Vulnerability – Part 1.5 – The Info Leak – Green Tech.The vulnerability itself is not especially interesting, but the process of finding and understanding it was fun so I wanted to write about that.Triggering this is extremely simple and includes exactly three steps:.I looked at the hyper-v manager and nothing shows up there either.Intermediate drivers rely on the lowest level drivers to function.The first time this function is Windows kernel internals, it calls EtwpRegisterTpNotificationOnce : Without getting into too many internal details about waits and the thread pool, this function essentially creates an event with the callback function EtwpNotificationThread and then calls NtTraceControl with an Operation value of 27 — an undocumented and unknown value.

Then, in EtwpQueueNotification , immediately after a notification is added to the notification queue for the process, this event is signaled:.The event being signaled makes the EtwpNotificationCallback get called, since it was registered to wait on this event, so it is, in a way, an ETW notification callback that is being notified whenever the process receives an ETW notification.

Luckily, it has a way to do that.This operation requires no input arguments — it simply returns the first queued notification.This gives EtwpNotificationThread all the information that it needs to reply to that last queued notification quietly, without disturbing the unaware caller that simply asked it to register a provider.

After replying, the event is set to a waiting state again, to wait for the next notification to arrive.Most of this pretty long explanation has nothing to do with this vulnerability, which really is pretty small and simple and can be explained in a much less complicated way.But I did say this post was mostly an excuse to dump some more obscure ETW knowledge in hope that one day someone other than me will read it and find it helpful, so you all knew what you were getting into.

And now that we have all this unnecessary background, we can look at the vulnerability itself.The issue is actually in the last part we talked about — returning the last queued notification.And this is the same structure that can be retrieved using NtTraceControl with EtwReceiveNotification operation… Does that mean that we get a free kernel pointer by calling NtTraceControl with the right arguments?

Not exactly.To be precise, you get half of a kernel pointer.And after copying the data to the user-mode buffer, they set the value of RegIndex , which should overwrite the kernel pointer that is in the same union:.

So setting RegIndex only removes the bottom half of the pointer, leaving the top half to be returned to the caller:.Triggering this is extremely simple and includes exactly three steps:.In fact, since the NonPagedPool is sized 16TB or 0x bytes , this vulnerability tells us exactly where the NonPaged pool is, and we can validate that in the debugger:.System Region Base Address NumberOfBytes SecureNonPagedPool : ffff KernelShadowStacks : ffff PagedPool : ffff8a NonPagedPool : ffff9d SystemCache : ffffb SystemPtes : ffffc UltraZero : ffffd Session : ffffe PfnDatabase : ffffe c PageTables : fffff SystemImages : fffff Cfg : fffffaf0ead0 HyperSpace : fffffd KernelStacks : fffffe I believe that when this code was introduced, it was completely safe — those areas of the code are pretty ancient and get very few changes.

This code was probably introduced in the days before x64 , when the size of a pointer and the size of a ULONG was the same, so setting RegIndex did overwrite the whole object address.When x64 changed the size of a pointer, this code was left behind and was never updated to match this, so this bug appeared.This makes you wonder what similar bugs might exist in other pieces of ancient code that even Microsoft forgot about?

In case you want to see the three lines of code that trigger this bug, you can find them here.You must be logged in to post a comment.Skip to content Introduction This post is not actually directly related to the first one and does not use CVE More ETW Internals! The first time this function is called, it calls EtwpRegisterTpNotificationOnce : Without getting into too many internal details about waits and the thread pool, this function essentially creates an event with the callback function EtwpNotificationThread and then calls NtTraceControl with an Operation value of 27 — an undocumented and unknown value.

Then, in EtwpQueueNotification , immediately after a notification is added to the notification queue for the process, this event is signaled: The event being signaled makes the EtwpNotificationCallback get called, since it was registered to wait on this event, so it is, in a way, an ETW notification callback that is being notified whenever the process receives an ETW notification.

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.

And though it shouldn’t be needed, what if you right-click that shortcut and run it “as administrator”? BTW, that shortcut ends up running WindowsSandbox So, I’ve enabled all the pre-requisites and Windows Sandbox; but when I attempt to start it I just get the blue and white logo splash screen

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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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  2. The first time this function is called, it calls EtwpRegisterTpNotificationOnce : Without getting into too many internal details about waits and the thread pool, this function essentially creates an event with the callback function EtwpNotificationThread and then calls NtTraceControl with an Operation value of 27 — an undocumented and unknown value.
  3. I found a tutorial that setup a config file that opened the do
  4. Each application is responsible for drawing or refreshing its own windows and menus, in response to these messages.
  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.
Hacking Livestream #28: Windows Kernel Debugging Part I, time: 1:56:05

Windows Kernel Internals Blog

Microsoft Windows components.Hari Pulapaka on Apr 06 PM.

Windows Kernel Internals Process Architecture – properties

  • In fact, since the NonPagedPool is sized 16TB or 0x bytesthis vulnerability tells us exactly where the NonPaged pool is, and we can validate that in the debugger:!
  • Enabling Remote Work.
  • So, I’ve enabled all the pre-requisites and Windows Sandbox; but when I attempt to start it I just get the blue and white logo splash screen
  • 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.
  • Kernel Data Protection KDP is a new technology that prevents data corruption attacks by protecting parts of the Window
  • To be precise, you get half of a kernel pointer.
  • Then, as we saw in the previous blog post, the notification gets added to a reply queue and is waiting for a reply.
  • Mahjong Minesweeper.

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The existence of this field implies that you can reply to an ETW event.But no one ever told you that you can reply to an ETW notification, how would that even work? Normally, ETW works just the way you were told.Then, as we saw in the previous blog post, the notification gets added to a reply queue and is waiting for a reply.

Remember, there can only be 4 queues notifications waiting for a reply at any moment.When that happens, any process which registered for that provider has its registered callback notified and has a chance to reply to the notification using EtwReplyNotification.When someone replies to the notification, the original notification gets removed from the queue and the reply notification gets added to the reply queue.

The only case I could see so far where a reply is sent to a notification is immediately after a GUID is enabled — sechost! EnableTraceEx2 which is the standard way of registering a provider and enabling a trace has a call to ntdll! ReplyRequested set to 1.Specifically, in this case, something a little more complicated happens.So to do this, it uses a trick.Without getting into too many internal details about waits and the thread pool, this function essentially creates an event with the callback function EtwpNotificationThread and then calls NtTraceControl with an Operation value of 27 — an undocumented and unknown value.

Since this field is a pointer and not a list, it can only contain one event at a time.Then, in EtwpQueueNotification , immediately after a notification is added to the notification queue for the process, this event is signaled:.The event being signaled makes the EtwpNotificationCallback get called, since it was registered to wait on this event, so it is, in a way, an ETW notification callback that is being notified whenever the process receives an ETW notification.

Luckily, it has a way to do that.This operation requires no input arguments — it simply returns the first queued notification.This gives EtwpNotificationThread all the information that it needs to reply to that last queued notification quietly, without disturbing the unaware caller that simply asked it to register a provider.After replying, the event is set to a waiting state again, to wait for the next notification to arrive.

Most of this pretty long explanation has nothing to do with this vulnerability, which really is pretty small and simple and can be explained in a much less complicated way.But I did say this post was mostly an excuse to dump some more obscure ETW knowledge in hope that one day someone other than me will read it and find it helpful, so you all knew what you were getting into.

And now that we have all this unnecessary background, we can look at the vulnerability itself.The issue is actually in the last part we talked about — returning the last queued notification.And this is the same structure that can be retrieved using NtTraceControl with EtwReceiveNotification operation… Does that mean that we get a free kernel pointer by calling NtTraceControl with the right arguments?

Not exactly.To be precise, you get half of a kernel pointer.And after copying the data to the user-mode buffer, they set the value of RegIndex , which should overwrite the kernel pointer that is in the same union:.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.And though it shouldn’t be needed, what if you right-click that shortcut and run it “as administrator”? BTW, that shortcut ends up running WindowsSandbox So, I’ve enabled all the pre-requisites and Windows Sandbox; but when I attempt to start it I just get the blue and white logo splash screen

: Learn mo

Leave a comment.I found a tutorial that setup a config file that opened the do

  • Remember that the first thing you learn about ETW notifications are that they are asynchronous?
  • MVP Award Program.
  • The architecture of Windows NTa line of operating systems produced and sold by Microsoftis a layered design that consists of two main components, user mode and kernel mode.
  • Immediately shut down.
  • In particular hardware abstraction does not involve abstracting the instruction set, which generally falls under the wider concept of portability.

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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.Starting with Windows XP , Microsoft began making bit versions of Windows available; before this, there were only bit versions of these operating systems.

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.Kernel mode in Windows NT has full access to the hardware and system resources of the computer.The Windows NT kernel is a hybrid kernel ; the architecture comprises a simple kernel , hardware abstraction layer HAL , drivers, and a range of services collectively named Executive , which all exist in kernel mode.

The user mode layer of Windows NT is made up of the “Environment subsystems”, which run applications written for many different types of operating systems, and the “Integral subsystem”, which operates system-specific functions on behalf of environment subsystems.The kernel mode stops user mode services and applications from accessing critical areas of the operating system that they should not have access to.

The kernel sits between the hardware abstraction layer and the Executive to provide multiprocessor synchronization , thread and interrupt scheduling and dispatching, and trap handling and exception dispatching.The kernel is also responsible for initializing device drivers at bootup.Kernel mode drivers exist in three levels: highest level drivers, intermediate drivers and low-level drivers.Windows Driver Model WDM exists in the intermediate layer and was mainly designed to be binary and source compatible between Windows 98 and Windows The lowest level drivers are either legacy Windows NT device drivers that control a device directly or can be a plug and play PnP hardware bus.

The interface between user mode applications and operating system kernel functions is called an “environment subsystem.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.

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After replying, the event is set to a waiting state again, to wait for the next notification to arrive.Most of this pretty long explanation has nothing to do with this vulnerability, which really is pretty small and simple and can be explained in a much less complicated way.

But I did say this post was mostly an excuse to dump some more obscure ETW knowledge in hope that one day someone other than me will read it and find it helpful, so you all knew what you were getting into.And now that we have all this unnecessary background, we can look at the vulnerability itself.The issue is actually in the last part we talked about — returning the last queued notification.

And this is the same structure that can be retrieved using NtTraceControl with EtwReceiveNotification operation… Does that mean that we get a free kernel pointer by calling NtTraceControl with the right arguments? Not exactly.To be precise, you get half of a kernel pointer.And after copying the data to the user-mode buffer, they set the value of RegIndex , which should overwrite the kernel pointer that is in the same union:.

So setting RegIndex only removes the bottom half of the pointer, leaving the top half to be returned to the caller:.Triggering this is extremely simple and includes exactly three steps:.In fact, since the NonPagedPool is sized 16TB or 0x bytes , this vulnerability tells us exactly where the NonPaged pool is, and we can validate that in the debugger:.System Region Base Address NumberOfBytes SecureNonPagedPool : ffff KernelShadowStacks : ffff PagedPool : ffff8a NonPagedPool : ffff9d SystemCache : ffffb SystemPtes : ffffc UltraZero : ffffd Session : ffffe PfnDatabase : ffffe c PageTables : fffff SystemImages : fffff Cfg : fffffaf0ead0 HyperSpace : fffffd KernelStacks : fffffe I believe that when this code was introduced, it was completely safe — those areas of the code are pretty ancient and get very few changes.

This code was probably introduced in the days before x64 , when the size of a pointer and the size of a ULONG was the same, so setting RegIndex did overwrite the whole object address.When x64 changed the size of a pointer, this code was left behind and was never updated to match this, so this bug appeared.This makes you wonder what similar bugs might exist in other pieces of ancient code that even Microsoft forgot about?

In case you want to see the three lines of code that trigger this bug, you can find them here.You must be logged in to post a comment.

Skip to content Introduction This post is not actually directly related to the first one and does not use CVE More ETW Internals! The first time this function is called, it calls EtwpRegisterTpNotificationOnce : Without getting into too many internal details about waits and the thread pool, this function essentially creates an event with the callback function EtwpNotificationThread and then calls NtTraceControl with an Operation value of 27 — an undocumented and unknown value.

Then, in EtwpQueueNotification , immediately after a notification is added to the notification queue for the process, this event is signaled: The event being signaled makes the EtwpNotificationCallback get called, since it was registered to wait on this event, so it is, in a way, an ETW notification callback that is being notified whenever the process receives an ETW notification.The InfoLeak The issue is actually in the last part we talked about — returning the last queued notification.

In fact, since the NonPagedPool is sized 16TB or 0x bytes , this vulnerability tells us exactly where the NonPaged pool is, and we can validate that in the debugger:! Just Show Me the Code Already! Leave a comment.Cancel reply You must be logged in to post a comment.Microsoft Edge Insider.Azure Databases.

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Windows Kernel Architecture part1, time: 5:26
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