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!
Tools like Application Verifier exist to find these kind of issues, but I could not get it to work so I had to roll my own. In case you are wondering, this byte array translates to an SMS message which gives us the password for this level. We Run the program and land at the second breakpoint. This is a community effort and we accept pull requests! See the CONTRIBUTING document for more information. If you have any questions you can always contact us or open an issue.
StepOver/step/sto/st¶
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.
Learn how to use memory breakpoints and hardware breakpoints effectively in x64dbg to debug complex software issues.
We will solve that level today, with the help of x64dbg. In the world of reverse engineering and debugging, understanding the differences between Memory Breakpoints and Hardware Breakpoints in x64dbg is crucial. This article will provide a detailed explanation of these two concepts and highlight the key differences between them. I found that you can greatly increase the likelyhood of this happening when your PC has been on for a few days and you have 70k handles open.
Understanding the Difference: Memory Breakpoints vs Hardware Breakpoints in x64dbg
- Apart from all the programming and social fun I had, I also stumbled upon a daunting CTF challenge made by a team from Avast.
- Among the puzzles there was a particularity interesting one – a binary that self-decrypted its code twice to reveal a secret message!
- I found that you can greatly increase the likelyhood of this happening when your PC has been on for a few days and you have 70k handles open.
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 xdgb address is accessed, while Hardware Breakpoints are triggered when a specific instruction is executed.
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.
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.
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!