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There are many fields in Computer Science, and tech in general, where you’ll want a lab with multiple VMs, containers, or even physical devices running various services. When learning networks, it’s useful to have a local lab. Another example is when doing Reverse Engineering, we sometimes want to work on an ARM processor instead of our desktop x86 processor, so we create a VM.
You get the idea. At some point in your career, you’ll find yourself surrounded by many hosts running services in different ports. Not having a system to reference your host can become a source of confusion. For example, if you stop for the weekend, the following Monday you have to go through your history to figure out if you were using port 2222 or port 2223 to ssh to the VM you were working on last week. In this short post, I’ll show you some techniques I use to keep my lab organised.
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If you want to get into mobile security or reverse engineering, you’ll get to a point when you would like to have access to an ARM processor. There are many devices you could use, but one very cheap (in price not in quality) is the Raspberry pi. You can get one for about 35$, which opens up the doors to a lot of learning. But sometimes you don’t want to carry an additional device, so what to do? Well, you can run a virtual machine that is ARM-based. That is what we are going to explore in this short post, how to install Raspbian OS using QUEMU so you can create your own ARM lab.
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Many people have heard about the perils of buffer overflows, but it’s something different to hear about it and another to try to make one yourself and play with it. In this post, we’ll explore the basics of buffer overflow and create an example to understand them better.
We’ll be using radare2, so if you need to install it, go ahead and read the instructions in their GitHub repository.
Let’s start by creating a small program to analyse and exploit with a buffer overflow.
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When reversing a binary, sometimes it’s useful to modify how the binary behaves. We can accomplish this by changing the binary itself. If we had the source code, it’d be easy, but for us, it’ll require looking at the decompiled code and deciding which bytes to modify to get our desired behaviour. We can, for example, change the control flow by changing the jump condition. Or we could modify a string that is used on a comparison, etcetera. The modification of a binary is known as patching. In this post, we are going to learn how to use radare2 to patch a binary.
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I’ve been exploring reverse engineering, and it’s a fascinating topic. There are many ways to analyse a binary. Usually, the analysis is divided into two types, static and dynamic. Static analysis is when you decompile the binary and read the assembly code and try to figure out what it does. On the other hand, in dynamic analysis, you execute the binary and analyse it while running. In general, for dynamic analysis, we use a debugger. As you can imagine, there are many debuggers out there. In this post, we are going to use LLDB to analyse a binary. I’ll explain the basic commands we would use and a general setup that I find useful when doing dynamic analysis.
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This is going to be a small article on the basics of working with Assembly Language. We won’t go deep into building extensive programs in assembly. The main idea of this post is to clarify the workflow for creating an assembly program and some key concepts so you can comfortably begin your assembly explorations.
Let’s first learn about the different assembly syntaxes and types.
Bash Beyond Basics
Increase your efficiency and understanding of the shell
If you are interested in this topic you might enjoy my course Bash Byond Basics.
This course helps you level up your bash skills. This is not a course on shell-scripting, is a course on improving your efficiency by showing you the features of bash that are seldom discussed and often ignored.
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Having a virtual machine running macOS opens up a lot of opportunities for learning. If you are into security, you can set up a VM for your security lab. Or if you want to learn networking or kernel debugging, it is also helpful to use a VM. The other option is risk breaking your work machine in your experiments (not fun). To build our VM, we need to use Disk Images, another topic that is useful in other areas.
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Apple provides the Launch Services API so we can interact with different applications from our current process. We can define URL schemes for our apps, and when that URL is opened, our app gets launched. We can also specify which application to open when a file associated with a specific Uniform Type Identifier (UTI) is being opened. This is registered in the Launch Services database. In this post, I’ll show you how to interact with the Launch Services API to register URL schemes and UTIs.
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If you’ve used the Swift Package Manager, you have interacted with its handy command-line tool. When creating command-line tools, we strive to provide an easy to use interface. One of the main characteristics of a good CLI tool is how it handles parameters. In this post, I’ll show you how to use Swift Package Manager’s TSCUtility module, and especially ArgumentParser to parse arguments for your swift command-line tools.
Let’s start by defining the common types of arguments we get in command-line tools:
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State machines are used to model systems that can be thought of as a collection of states, and a collection of events that cause state changes. Many of the systems we want to model can be abstracted to a state machine. For example, elements in a Game, devices like vending machines, ATMs, etcetera. In this post, I’ll explain what State machines are, and give a simple example of the implementation of a general state machine.
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