Published in category Project
on Christian Mayer's Weblog.

I’m very interested to reverse engineer and crack programs. This is an interesting thing because you need to deal with Assembly. When you understand Assembly you can think like a computer. And you can read every binary of almost every CPU architecture.

I created a PHP script for manipulating Mach-O binaries. This is useful to manipulate dynamically Mach-O files. It’s like a Hex Editor for PHP programmers, if you like. But it doesn’t matter if you are using a real Hex Editor or just a script — you need to know what you’re doing. You need do understand Assembly. Why with PHP? — Why not? I like PHP.

Overwriting the right values is easy. Especially when you overwrite an existing function or subroutine of a program with NOPs. But appending new functionality to an existing program is very hard because you need to change the size and offset values in the Mach-O header informations.

Update, 2015-02-18: I removed the arrays and use objects. This is prettier.

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About the Author

Christian is a professional software developer living in Vienna, Austria. He loves coffee and is strongly addicted to music. In his spare time he writes open source software. He is known for developing automatic data processing systems for Debian Linux.