Windows Internals: Windows Kernel - Part 1#

The Windows Kernel is the core component of the Windows operating system, responsible for managing the system’s resources and providing the interface for user programs to access the hardware. It is the most essential part of the system, and its stability and performance are critical for the overall operation of the computer.

The kernel is the foundation of the Windows operating system. It is responsible for managing the system’s resources, such as memory, processes, and devices. It also provides an interface for user programs to access the hardware. The kernel is designed to be small and efficient, while providing a robust and secure environment.

The Windows kernel is written in C and C++, and is divided into two parts: the executive and the kernel mode components. The executive is responsible for managing system resources, such as threads and processes, and provides an interface for user programs to access hardware. It also provides services such as memory management, security, and networking. The kernel mode components are responsible for low-level system operations, such as managing hardware interrupts and scheduling threads.

The kernel is responsible for managing the system’s resources, such as memory, processes, and devices. It also provides an interface for user programs to access the hardware. It is designed to be small and efficient, while providing a robust and secure environment. The kernel is optimized for performance and is designed to be responsive to user input. It is also designed to be highly reliable, so that it can handle unexpected situations without crashing or degrading performance.

The kernel is also responsible for handling hardware interrupts and scheduling threads. It is also responsible for managing the system’s memory, including virtual memory and physical memory. It also handles the system’s input/output operations, such as reading and writing data to and from disks.

The Windows kernel is constantly being improved and updated to provide better performance and security. As new hardware and software are introduced, the kernel must be updated to take advantage of the new features. The kernel is also responsible for handling security, ensuring that only authorized users can access the system.

The Windows kernel is a critical part of the Windows operating system, and its reliability and performance are essential for the overall operation of the computer. It is designed to be small and efficient, while providing a robust and secure environment. By keeping the kernel updated and optimized, users can ensure that their systems remain stable and secure.

Practical case, PowerShell#

PowerShell is a command-line tool that can be used to interact with the Windows kernel. It allows administrators to run commands to manage and configure Windows systems, as well as to write scripts to automate tasks. With PowerShell, users can access system functions, manage processes, query data sources, and interact with Windows services. It is also an effective tool for troubleshooting and diagnosing Windows system issues.

For example:

# Get the Windows Kernel Version
$os_info = Get-CimInstance Win32_OperatingSystem
$os_info.Version

# Output
6.3.9600.17238

Another Powershell example work with windows kernel components:

$bitness = (Get-WmiObject Win32_Processor | Select-Object AddressWidth).AddressWidth

#Check processor bit
if ($bitness -eq "64") {
    #Create instance of the Windows Driver Kit (WDK)
    $wdk = New-Object System.Management.ManagementClass("\\.\root\wmi", "MSWDI_WDK_Driver", $null)

    #Get an array of kernel components
    $components = $wdk.Get("KernelComponents")

    #Loop through each component
    foreach ($component in $components) {
        #Write the information to the console
        Write-Host "Component Name: $($component.ComponentName)"
        Write-Host "Component Path: $($component.ComponentPath)"
    }
} else {
    Write-Error "This script only works on 64-bit systems!"
}

Practical experiment. Working with WinAPI C++#

C++ code snippet for working with windows kernel components:

// Include the Windows kernel components 
#include <Windows.h> 

// Declare global variables 
HANDLE hDevice;
 
// Function to open a device handle 
BOOL OpenDevice(LPSTR lpDeviceName) 
{ 
    hDevice = CreateFile(lpDeviceName, 
        GENERIC_READ | GENERIC_WRITE, 
        0, 
        NULL, 
        OPEN_EXISTING, 
        0, 
        NULL); 

    // Check if the handle was successfully created 
    if (hDevice == INVALID_HANDLE_VALUE) 
        return FALSE; 
    else 
        return TRUE; 
} 

// Function to close the device handle 
BOOL CloseDevice() 
{ 
    if (CloseHandle(hDevice) == 0) 
        return FALSE; 
    else 
        return TRUE; 
} 

// Function to send an IOCTL to the device 
BOOL SendIoctl(DWORD dwIoControlCode, 
               LPVOID lpInBuffer, 
               DWORD nInBufferSize, 
               LPVOID lpOutBuffer, 
               DWORD nOutBufferSize, 
               LPDWORD lpBytesReturned) 
{ 
    if (DeviceIoControl(hDevice, 
                        dwIoControlCode, 
                        lpInBuffer, 
                        nInBufferSize, 
                        lpOutBuffer, 
                        nOutBufferSize, 
                        lpBytesReturned, 
                        NULL) == 0) 
        return FALSE; 
    else 
        return TRUE; 
} 

// Main function 
int main() 
{ 
    // Open the device handle 
    if (OpenDevice("\\\\.\\MyDevice") == FALSE) 
    { 
        printf("Error opening device.\n"); 
        return 0; 
    } 

    // Allocate memory for the input and output buffers 
    LPBYTE lpInBuffer = (LPBYTE) malloc(1024); 
    LPBYTE lpOutBuffer = (LPBYTE) malloc(1024); 
    DWORD dwBytesReturned; 

    // Set the input buffer data 
    lpInBuffer[0] = 0x1; 

    // Send the IOCTL to the device 
    if (SendIoctl(IOCTL_MY_DEVICE_CONTROL_CODE, 
                  lpInBuffer, 
                  1024, 
                  lpOutBuffer, 
                  1024, 
                  &dwBytesReturned) == FALSE) 
    { 
        printf("Error sending IOCTL.\n"); 
        return 0; 
    } 

    // Print the output buffer data 
    for (int i = 0; i < dwBytesReturned; i++) 
        printf("%d ", lpOutBuffer[i]); 

    printf("\n"); 

    // Free the allocated memory 
    free(lpInBuffer); 
    free(lpOutBuffer); 

    // Close the device handle 
    CloseDevice(); 

    return 0; 
}

Windows kernel debugging#

Kernel debugging is a powerful and important tool for troubleshooting and analyzing Windows systems. It provides access to the very core of the operating system and helps you to identify and troubleshoot issues that can’t be solved with other tools. In this blog post, we’ll take a look at the basics of kernel debugging, some of its common uses, and how to get started with it.

Kernel debugging is a process of connecting a debugger to a running Windows system. This allows you to view the internal state of the system and analyze the code that is running. The process involves connecting a debugger to the system, setting breakpoints, and examining the system state. The debugger can be either a local or remote debugger, depending on the needs of the analysis.

Common uses of kernel debugging include analyzing system crashes, identifying driver issues, and troubleshooting system performance problems. By examining the system state at the time of a crash, you can identify the root cause of the issue and take corrective action. Additionally, kernel debugging can be used to analyze and identify driver issues, such as incorrect driver installation or issues with driver compatibility. Finally, kernel debugging can also be used to troubleshoot system performance problems, such as high CPU usage or slow application start-up times.

To get started with kernel debugging, the first step is to connect the debugger to the system. This can be done either locally or remotely, depending on the requirements of the analysis. Once the debugger is connected, you can then set breakpoints and examine the system state. You can also configure the debugger to automatically break when certain conditions are met, such as when a specific driver is loaded.

With kernel debugging, you can gain insight into the inner workings of Windows and identify and troubleshoot issues that can’t be solved with other tools. If you’re looking to take your Windows troubleshooting skills to the next level, then learning how to use kernel debugging is a great place to start.

Windbg#

Using Windows windbg tool commands example

Windbg is a powerful debugging tool used to analyze and troubleshoot application crashes and other software issues. Below are some example commands:

  1. !analyze –v: This command is used to analyze the current state of the application and generate a report of the debugging process.

  2. !loadby: This command is used to load a specific debugging module, such as the symbol file or the debugging engine.

  3. !thread: This command is used to display information about the current thread and its related objects, such as the stack trace and the call stack.

  4. !peb: This command is used to display the process environment block which contains information about the application’s environment, such as the current working directory and the command line arguments.

  5. .reload: This command is used to reload the symbol files, allowing for updated debugging information.

  6. .ecxr: This command is used to display the current context record, which contains information about the current register values and other state information.

  7. .lastevent: This command is used to display the last event that caused the application to crash.

  8. !dumpstack: This command is used to display the current call stack, which contains a list of the functions that have executed up to the point of the application crash.