Each load command includes meta-information, such as type of command, its name, position in a binary and so on.įunction prologue - a few lines of code at the beginning of a function, which prepares the stack and registers for use within the function.Įntrypoint - refers to the starting address within the code section that will be executed.īundle - is a macOS file directory with a defined structure and file extension, allowing related files to be grouped together as a conceptually single item.Ĭode cave - a section in memory or binary that is usually null bytes or bytes that can be overwritten with new bytes. Load commands - kind of a table of contents, that describes position of segments, symbol table, dynamic symbol table, etc. Header - contains general information about the binary: byte order (magic number), cpu type, amount of load commands, etc. Nm - command to list symbols from object files. The otool command displays specified parts of object files or libraries. Mach-O - short for Mach Object file format, is a file format for executables, object code, shared libraries, dynamically-loaded code, and core dumps.ĭylib - macOS dynamically loaded shared library. Since late 2019, I've been able to implement this technique in shellcode. The history of dylib loading technique was first notably mentioned in 2015 and has been used in the wild in late 2019. This workshop is a way to share knowledge with other offensive teams as well as defenders looking to instrument protections.
Since switching to an offensive role, I've been designing implants for various environments. A basic disassembler (objdump works too).macOS environment (Mojave 10.14 or Catalina 10.15).macOS specific assembly routines for shellcode.Designing an assembly trampoline for entrypoint manipulation.You will be compiling Go libraries, assembly patching target Mach-O binaries, and loading a dylib into memory. The topics covered will include compiling Go dylibs, parsing Mach-O headers, binary code caves, binary entrypoint redirection, typical assembly routines used in shellcode, and understanding the Mach-O load order. The content will cover developing stager code and shellcode for dynamic library injection in macOS environments (Mojave 10.14 & Catalina 10.15) with Golang compiled binaries. This workshop is designed for those looking to develop offensive tooling or learning the technique for defense purposes.
MacOS Dylib Injection through Mach-O Binary Manipulation
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