Hello, my name is Typhoon and today we are embarking on an exciting journey into the realm of cybersecurity,
where we will unravel the intricacies of Shellcode.
And in this detailed lecture we will explore the concepts of Shellcode, its purpose and its role in
buffer overflow attacks and dissect a practical example step by step.
So now let's delve right in the Shellcode a term originally rooted in reverse shell creation was a pivotal
role in the realm of cyber exploits.
Unlike shell scripting, which involves scripting bash commands, Shellcode engages directly with a
program's registers and functions to accomplish specific outcomes.
Shellcode is written in assembly language and then translated into hexadecimal Opcodes.
So these opcodes interact with the program to manipulate its behavior and achieve specific goals.
So it becomes especially relevant when exploiting vulnerabilities in software systems.
So the complexity of the vulnerability determines the length and intricacy of the shellcode required.
So one of the intriguing features of Shellcode is its efficiency.
So by providing tailored inputs to a program, Shellcode can effectively trigger actions like spawning
a reverse shell.
So this efficiency makes Shellcode a powerful tool for cyber attacks, and particularly in situations
where vulnerabilities are exposed.
And now let's delve into an illustrative example to solidify our understanding.
Now we will open our Visual Studio code here.
We'll create a new file.
And my.
New Shellcode example.
See here and save it on the desktop or whatever folder you like here and now.
We will firstly write our code and then I will explain this code line by line.
So we will include the Stdio dot h here.
Um, and after that, we will create our main function.
Other arguments here.
Character Array.
Who?
Zero is.
Been.
Age.
Arguments.
One going to be a new.
And also X.
Here we.
Zig zag.
We.
And after that been again.
And here we will pass arcs again.
And as a third parameter, we will pass null.
And after that, here we will we have completed our code and we will just return with the zero here.
Returns zero.
So here now I will explain this code line by line.
And at first, at first line, this line includes the standard input output library header, enabling
input and output operations.
This is the main function declaration where the program execution begins from here and we have created
a arguments array of size two is declared to hold the command line arguments and here we have arguments.
Zero.
This is the first element of arcs is assigned the path of the shell executable here.
In this case it's been as h for Linux and args one.
Here is the this is the second element of arcs is set to null indicating the end of the argument list.
And also we have zig zag or pronounce it.
This is the this function is invoked to execute the shell beans with the provided arguments.
So this essentially spawns a new shell process.
And also we have return zero.
This function returns zero indicating successful execution.
So this code, when compiled and modified, can be transformed into input strings usable against vulnerable
programs.
Gain shell Access.
The exec functions role here is to execute the shell, inheriting the permissions of the target program.
So shell code is frequently employed in buffer overflow attacks.
And in a sense, a buffer overflow attack occurs when a program writes data exceeding allocated memory,
potentially leading to crashes, data overwrites or unintended code execution.
So to conclude, shell code is a potent tool for exploiting software vulnerabilities.
Its direct interaction with a program internals enables specific outcomes or exploration has also illuminated
its role in buffer overflow attacks, emphasizing its significance in cyber security.