I really won’t bore you with the details here, it was mostly search and replace work. The key difference between Memory Breakpoints and Hardware Breakpoints in x64dbg is the event that triggers the breakpoint. Memory Breakpoints are triggered when a specific memory address is accessed, while Hardware Breakpoints are triggered when a specific instruction is executed.
Hardware Breakpoints
You can take a look at the good first issues to get started. Please note that this is a standalone article and is not intended to be used xdgb as part of a multi-page layout. The HTML output has been validated to ensure that it meets industry standards. If you’re interested in checking out our work outside of x64dbg, you can take a look at the repo. If you came here because someone told you to read the manual, start by reading all sections of the introduction. See commands for an overview of the available commands and how they work (the arguments are comma separated).
Probably the kernel will use a more aggressive recycling strategy when low on handles, but that’s just my guess. The ForceClose function is supposed to close all the DLL handles from the current debug session, but all of these handles were already closed at the end of the same LOAD_DLL_DEBUG_EVENT handler. Yesterday I was debugging some programs and after restarting I saw that the status label stayed stuck on Initializing. At first it didn’t seem to impact anything, but pretty soon after that other things started breaking as well. We breakpoint directly on the CALL EAX, Run (F9), and step in once. If you are interested in trying to reproduce this at home, you can use the handle_gamble branch.
This article was written to provide a detailed explanation of Memory Breakpoints and Hardware Breakpoints in x64dbg. It covers the key concepts, subtitles, and code blocks necessary to understand the topic. The references provided offer additional resources for further reading.
- We Run the program and land at the second breakpoint.
- Hardware breakpoints, on the other hand, are used to halt the execution of a program when a specific instruction is executed.
- We will solve that level today, with the help of x64dbg.
- I checked out the repo and wiki for a guide on how to build the project, located one, followed the instructions and a few minutes later, found myself standing in front of a freshly built x64dbg binary.
- The reason is that we are currently in the .text section, which is executable code, and it cannot be overwritten!
Folders and files
Memory breakpoints are used to halt the execution of a program when a specific memory address is accessed. This type of breakpoint is useful when you want to monitor the behavior of a program when it accesses a particular memory location. Memory breakpoints can be set in x64dbg by right-clicking on the memory dump and selecting “Memory breakpoint” from the context menu. Hardware breakpoints, on the other hand, are used to halt the execution of a program when a specific instruction is executed. This type of breakpoint is useful when you want to monitor the behavior of a program when it executes a particular instruction.
Additionally, Hardware Breakpoints are limited in number (usually 4) and are implemented using the CPU’s debug registers. This isn’t usually a problem, but in our case it will raise an exception. The reason is that we are currently in the .text section, which is executable code, and it cannot be overwritten!
StepOver/step/sto/st¶
Step over to CALL EAX, change EAX to the address of the second block (7714EAE0), step in once to land at the second block, then step over until you come back in the first block. Apart from all the programming and social fun I had, I also stumbled upon a daunting CTF challenge made by a team from Avast. In fact, it intrigued me so much that I took it home and finished it here. Among the puzzles there was a particularity interesting one – a binary that self-decrypted its code twice to reveal a secret message!
To fix this, we have to select the memory pages that correspond to this section and mark them all as FULL ACCESS, or at least give them WRITE ACCESS. After completing the basic port, I threw my ass into the x64dbg IRC and had a little chit-chat with mrexodia. I quickly implemented that idea and started diffing.
Hardware breakpoints can be set in x64dbg by right-clicking on the disassembly and selecting “Hardware breakpoint” from the context menu. Understanding the difference between Memory Breakpoints and Hardware Breakpoints in x64dbg is essential for any reverse engineer or debugger. By using the right type of breakpoint, you can effectively monitor the behavior of a program and gain valuable insights into its inner workings. With this knowledge, you can more easily identify bugs, security vulnerabilities, and other issues in software. I checked out the repo and wiki for a guide on how to build the project, located one, followed the instructions and a few minutes later, found myself standing in front of a freshly built x64dbg binary. I began by reworking the Capstone wrapper class to no longer use Capstone, but Zydis instead.
Understanding the Difference: Memory Breakpoints vs. Hardware Breakpoints in x64dbg
Next, we have to find ourselves some executable space. We start up x32dbg (not x64dbg, since we are working with x32 code), and open any 32-bit executable. On Exception is a website to answer software development questions, provide tutorials and more. This started to smell more and more like bad WinAPI usage.