Driver Introspection with DriverMon

Saturday, November 18, 2017

In the past few weeks I've been working in my non-existent spare time on DriverMon - a driver monitoring tool for Windows. The tool is far from complete, but it's already quite useful. In this post I'll describe how to use it and some of the challenges of building such a tool. Initially I wanted to be able to track every I/O Request Packet (IRP) targeted to monitored devices. The term "devices" here is important, as the Windows I/O system is device-centric rather than driver-centric. That is, requests are delivered to devices, not drivers. A device can be thought of...
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Integrating COM IPC into Existing Executables

Friday, October 6, 2017

A few days ago at work, a requirement arouse to create some form of inter-process communication (IPC) between two cooperating processes where the source code for the executables themselves already existed, so such mechanism should integrate into the existing code as easily as possible, while providing bi-directional communication. Several options were brought up, including pipes and sockets. The processes are services and have no UI, so Window messages were not an option. Other ideas included shared memory with notifications using kernel event objects... and then I suggested COM. There was a brief silence and then people started murmuring things like "COM...
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Hooking COM Classes

Monday, August 7, 2017

There are some common scenarios that benefit from the ability to hook operations. The canonical example is hooking Windows API functions for debugging purposes, or for malware detection. In this scenario, some DLL is injected into a target process and then hooks relevant functions. There are several ways to do that, but that is not the focus of this post; the interested reader can search the web for more information. In the Component Object Model (COM) world, things are not so easy. Since COM is object based, it's not generally possible to get the address of a COM interface method,...
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Packaging Apps into Single Files

Tuesday, May 9, 2017

One of the hallmarks of easy-to-use tools is simple installation, preferably no installation at all. The classic example is the Sysinternals tools. Each tool is a single executable, self contained, and can be run from anywhere, including network shares and web locations. These tools have no dependencies (except for built-in Windows DLLs), or so it seems. One canonical example is Process Explorer that hides within it two binaries. The first is a kernel driver, used to extract information from the system that cannot be done from user mode (such as reading values of kernel variables), and the other is a 64...
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Sharing Code between Windows, WinRT and Windows Phone

Monday, December 16, 2013

In recent times, I often find myself developing for more than one “Windows” platform – typically Windows Phone and Windows 8 Store and sometimes Windows (WPF) as well. In this post, I’d like to share some of the tools and techniques I’ve been using to ease code sharing. Portable Class Libraries (PCLs) PCLs came out in Visual Studio 2012 and provide an easy way to create a single project that can be referenced by multiple project types. When you create a PCL, you get the following dialog: This dialog allows you to select multiple targeted platforms (at...

Color Gradient Generator

Tuesday, November 12, 2013

A while back, I created a WPF Mandelbrot Set program with zoom abilities. I demonstrated the use of async/await for writing code that works asynchronously (to keep the UI responsive), but is easy to write as synchronous code. Here’s a sample image:The image is grayscale, so I wanted to make it use colors, to indicate the level of “being part of” the Mandelbrot set. The problem here is how to create a nice color gradient that moves smoothly from color to color.One possible option might be to leverage an existing class, such as WPF’s LinearGradientBrush, set up a bunch...

MVVM View vs. Control

Sunday, November 3, 2013

In the MVVM world, Views are attached to ViewModels. How can a view be implemented? Typical answers for say, WPF, are: Window, User Control and Data Template. Similar answers exist for Windows Phone and Windows 8, where “Window” may be dropped or replaced by Page.This is certainly true, but about that User Control? Can any user control automatically be considered a View? Not quite.The distinction between view and control (user control or otherwise) is based on reusability and dependency. A View requires a ViewModel to give it context. A View cannot function without a ViewModel. Typical XAML View would...
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Using KeyedCollection<> instead of a Dictionary<>

Wednesday, October 23, 2013

The System.Collections.Generic.Dictionary<TKey, TValue> class is one of the most useful of all .NET collections. It maps a key to a value, and allows for fast retrieval based on the key, as it’s implemented as a hash table, calling GetHashCode on the key object to get to a specific “bucket”, and then looks up the actual value (with Object.Equals or a specific IEqualityComparer<Tkey>.Equals).One feature that Dictionary<> doesn’t support is the ability to access items by integer index. That is, insertion order is not maintained. For most cases, this may be ok, but some cases require fast search and index based...
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Tip: Turning Win32 Console app to non-Console app

Monday, September 30, 2013

Let’s say you’ve created a Win32 Console Application in Visual Studio:We get the classic main function.Now suppose that after working on the project for a while we want to turn the app into a Windows app – no console. At first, this seems easy: just replace the main function with a proper WinMain: int _tWinMain(HINSTANCE hInstance, HINSTANCE, LPTSTR lpCmdLine, int nCmdShow) Unfortunately, that’s not enough. Building the project produces the following linker error:MSVCRTD.lib(crtexe.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartupThe linker still expects a main function.The solution is (apart...
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Getting rid of the Start button – Adding a Hook

Monday, September 16, 2013

In the previous post we saw how to find and remove the start button and move the task bar window to the left to occupy the free space left by the former start button.However, we saw that by opening the system tray, the task bar moves back to its original position. We need to know when that happens, and then use the same trick to move it back to the “right” position.To do that we would need to register somehow for the WM_MOVE message. This is one option, and we can verify this using Spy++’s Message window for task...