Assembly Debugging with gdb

Introduction

Over the last couple of months I’ve spent quite a lot of time in gdb whilst working through the SLAE certification exam assignments. The question I had was how I could become more efficient when working in gdb? I wanted to have easier access to the register values and generally save myself time whilst debugging or analysing shellcode written in nasm assembly. I’ve been running gdb on an Ubuntu 16.04 LTS 32-bit system.

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SLAE Assignment 7: Custom Crypter

So I’m here at the start of the final assignment of the SLAE exam. Its certainly been a lot of fun working through each of the previous assignments and I’m expecting this one will be the same as the subject is encryption.

The assignment requires:

  • Create a custom crypter like the one shown in the SLAE crypters video lecture
  • Free to use any existing encryption schema
  • Can use any programming language

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Assembling and Compiling when writing shellcode

I’ve been working on the SecurityTube Linux Assembly Expert certification and thought I’d write about a couple of things I’ve come across which helped me to save quite a lot of time when writing the shellcode throughout the course and for the exam.

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SLAE Assignment 6: Polymorphic shellcode Part 3

In Assignment 6 create polymorphic versions of shellcode from the shell-storm web site. The actual assignment has the following requirements:

  • Take up at least 3 shellcodes from Shell-Storm and create polymorphic versions of them to beat pattern matching
  • The polymorphic versions cannot be larger than 150%
  • Bonus points for making it shorter in length than the original

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SLAE Assignment 6: Polymorphic shellcode Part 2

In Assignment 6 create polymorphic versions of shellcode from the shell-storm web site. The actual assignment has the following requirements:

  • Take up at least 3 shellcodes from Shell-Storm and create polymorphic versions of them to beat pattern matching
  • The polymorphic versions cannot be larger than 150%
  • Bonus points for making it shorter in length than the original

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SLAE Assignment 6: Polymorphic shellcode Part 1

In Assignment 6 create polymorphic versions of shellcode from the shell-storm web site. The actual assignment has the following requirements:

  • Take up at least 3 shellcodes from Shell-Storm and create polymorphic versions of them to beat pattern matching
  • The polymorphic versions cannot be larger than 150%
  • Bonus points for making it shorter in length than the original

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SLAE Assignment 5: Shellcode Analysis Part 3

Assignment 5 of the SLAE exam is a little different to the previous 4. The assignment asks for a number of shellcode samples to be analysed.

  • Take up at least 3 shellcode samples created using Msfvenom for linux/x86
  • Use GDB/Ndisasm/Libemu to dissect the functionality of the shellcode
  • Present your analysis

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SLAE Assignment 5: Shellcode Analysis Part 2

Just to review, the assignment asks for a number of shellcode samples to be analysed.

  • Take up at least 3 shellcode samples created using Msfvenom for linux/x86
  • Use GDB/Ndisasm/Libemu to dissect the functionality of the shellcode
  • Present your analysis

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SLAE Assignment 5: Shellcode Analysis Part 1

Assignment 5 of the SLAE exam is a little different to the previous 4. The assignment asks for a number of shellcode samples to be analysed.

  • Take up at least 3 shellcode samples created using Msfvenom for linux/x86
  • Use GDB/Ndisasm/Libemu to dissect the functionality of the shellcode
  • Present your analysis

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SLAE Assignment 4: Custom Encoder Scheme

The 4rd assignment of the SLAE certification focuses on creating a custom encoding schema and requires the following:

  • Create a custom encoding scheme similar to the “Insertion Encoder” example demonstrated in the course
  • Write a proof of concept using the execve-stack as the shellcode to encode with your custom schema.

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