simonemainardi

Disassemble and Modify an Binary To Change a Function

In this gist I show how to disassemble and modify a Linux executable binary to change the body of a function. This will allow you to control how a binary behaves, even when you don't have access to the source code and you can't recompile it.

In my case, I was asked to try and bypass the protection mechanism implemented. The protection mechanism implemented was meant to only allow a binary to be run in presence of a valid license.

So basically my activity involved:

• Finding the function which performs the protection check
• Disassembling the binary

genadyp

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

mortenscheel

#!/usr/bin/env bash
NC='\033[0m' # No Color
YELLOW='\033[0;33m'
CYAN='\033[0;36m'
GREEN='\033[0;32m'
RED='\033[0;31m'
MAGENTA='\033[0;35m'

notify_about_actions_required() {
    changed_files="$(git diff-tree -r --name-status --no-commit-id $1 $2)"