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  • Blog Post: Understanding Pool Corruption Part 3 – Special Pool for Double Frees

    In Part 1 and Part 2 of this series we discussed pool corruption and how special pool can be used to identify the cause of such corruption.  In today’s article we will use special pool to catch a double free of pool memory.   A double free of ...read more
  • Blog Post: What Did Storport Do With My I/O?

    In a previous article I showed how to track an I/O request from the filesystem, through the class driver, and to the storage driver.  In that article I concluded with " From this data we can usually assume that the request has been sent to the ...read more
  • Blog Post: Configuring a Hyper-V VM For Kernel Debugging

    Yesterday's blog prompted some questions about how to set up a debugger for a Windows OS running in a Hyper-V VM.   I was surprised that I wasn't able to find good, publicly available, Microsoft issued documentation for this configuration.   ...read more
  • Blog Post: My Kernel Debugger Won't Connect

    Hello ntdebugging readers, the Debug Ninja is back again with a quick blog this holiday season.   I recently encountered a situation where the kernel debugger could not connect to a Windows Server 2008 R2 system running in a Hyper-V virtual machine ...read more
  • Blog Post: Understanding Pool Corruption Part 1 – Buffer Overflows

    Before we can discuss pool corruption we must understand what pool is.  Pool is kernel mode memory used as a storage space for drivers.  Pool is organized in a similar way to how you might use a notepad when taking notes from a lecture or a ...read more
  • Blog Post: How the Clipboard Works, Part 1

    Recently I had the opportunity to debug the clipboard in Windows, and I thought I’d share some of the things I learned.   The clipboard is one of those parts of Windows that many of us use dozens (hundreds?) of times a day and don’t really think ...read more
  • Blog Post: Determining the source of Bug Check 0x133 (DPC_WATCHDOG_VIOLATION) errors on Windows Server 2012

    What is a bug check 0x133? Starting in Windows Server 2012, a DPC watchdog timer is enabled which will bug check a system if too much time is spent in DPC routines. This bug check was added to help identify drivers that are deadlocked or misbehaving.  ...read more
  • Blog Post: Debugging a Generation 2 Virtual Machine

    Hyper-V is based on the 440BX (PCI) chipset for emulation. The decision to use this chipset started years ago with Connectix Virtual PC.  The advantage of using an emulated chipset based on a popular motherboard like the 440BX, along with associated ...read more
  • Blog Post: How the Clipboard Works, Part 2

    Last time , we discussed how applications place data on the clipboard, and how to access that data using the debugger.   Today, we'll take a look at how an application can monitor the clipboard for changes.   Understanding this is important ...read more
  • Blog Post: Understanding Pool Corruption Part 2 – Special Pool for Buffer Overruns

    In our previous article we discussed pool corruption that occurs when a driver writes too much data in a buffer.  In this article we will discuss how special pool can help identify the driver that writes too much data.   Pool is typically organized ...read more
  • Blog Post: Great power. Great responsibility.

    When it comes to the registry, administrators are given great power to manually configure Windows to suit their needs, but even slight, seemingly innocuous changes to a particular key or value can have a drastic impact on basic operations of the system ...read more
  • Blog Post: What Should Never Happen... Did

    Hi, this is Bob Golding; I wanted to write a blog about an interesting hardware issue I ran into. Hardware problems can be tricky to isolate. I recently came across one that I thought was interesting and gave an example of how to trace code execution ...read more
  • Blog Post: Case of the Unexplained Services exe Termination

    Hello Debuggers! This is Ron Stock from the Global Escalation Services team and I recently worked an interesting case dispatched to our team because Services.exe was terminating. Nothing good ever happens when Services.exe exits. In this particular case ...read more
  • Blog Post: Identifying Global Atom Table Leaks

    Hi, it's the Debug Ninja back again with another debugging adventure.   Recently I have encountered several instances where processes fail to initialize, and a review of available resources showed that there was no obvious resource exhaustion.   ...read more
  • Blog Post: ResAvail Pages and Working Sets

    Hello everyone, I'm Ray and I'm here to talk a bit about a dump I recently looked at and a little-referenced memory counter called ResAvail Pages (resident available pages).   The problem statement was:  The server hangs after a while.   ...read more
  • Blog Post: Debugging a CLOCK_WATCHDOG_TIMEOUT Bugcheck

    Hi debuggers, Andrew Richards here for my first NT Debugging post. I thought I’d share a recent case that used a lot of discovery techniques to uncover the details of what was going on. Most bugchecks give you the information you need as arguments, but ...read more
  • Blog Post: Where Did My Disk I/O Go?

    Hello, Mr. Ninja back again.   I recently discovered that although my team often tracks I/O from the file system through to the disk controller, we have never publicly documented the steps required to do this.   This seems like a great opportunity ...read more
  • Blog Post: Call Stacks for Pool Allocations

    Hello, it's the Debug Ninja back again for another NtDebugging Blog article.   For as long as I can remember user mode debuggers have had an easy way to get call stacks for heap allocations.   On more recent versions of Windows this has been ...read more
  • Blog Post: Debugging a Crash, Found a Trojan

    Hi, I'm Manish from Global Escalation Services. I would like to present a multiple random bug check issue, which was caused by malicious code (trojan) running on the machine. This is the walkthrough of how we found the virus on the server. In this particular ...read more
  • Blog Post: Debugging a Debugger to Debug a Dump

    Recently I came across an instance where my debugger did not do what I wanted.  Rarely do computers disobey me, but this one was unusually stubborn.  There was no other option; I had to bend the debugger to my will.   There are many ways ...read more
  • Blog Post: Debugging a Network Connectivity Issue - TrackNblOwner to the Rescue

    Hello Debug community this is Karim Elsaid again.  Today I’m going to discuss a recent interesting case where intermittently the server is losing access to the network.  No communication (even pings) can be done from / to the server when the ...read more
  • Blog Post: Debugging Backwards: Proving root cause

    Matt Burrough here again.   On rare occasions when debugging, we'll actually know (or strongly suspect) what the root cause of a problem is at the beginning of our analysis - but we still need to investigate to confirm our assertion.   The following ...read more