Insert: Dylib

: Adding new functionality to an existing executable without access to its original source code.

| App Type | Action | |----------|--------| | CLI tool | Check env vars at startup, use hardened runtime | | GUI app | Enable + Library Validation in Xcode | | Daemon / privileged helper | Reject non-Apple-signed dylibs; use dlopen_preflight() | | Security-sensitive app | Use posix_spawn with clean environment, monitor dyld callbacks | insert dylib

is the process of forcibly loading a custom dynamic library into the address space of a running process (or a process about to launch). This technique is widely used for: : Adding new functionality to an existing executable

: If the binary is signed, the tool can strip the existing signature to prevent immediate crashes due to mismatched hashes. Common Use Cases Common Use Cases Modern macOS versions and hardened

Modern macOS versions and hardened applications impose significant restrictions on DYLD_INSERT_LIBRARIES :