macos-process-injection

A macOS security reference about inserting code into running or launching processes, including through dynamic libraries. A dynamic library is a reusable piece of program code loaded by an application.

In plain words
What is it for?
Use it to study library preloading, library hijacking, XPC and Mach techniques, Electron injection, and the requirements or restrictions that apply to them.
Why use it?
It explains which macOS protections, permissions, binary settings, and system restrictions affect process-injection techniques. The material is intended for authorized security research and testing.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/miru-zero/zero-brain/macos-process-injection
Any agent
npx skills add miru-zero/zero-brain --skill macos-process-injection
Clone the repo
git clone --depth 1 https://github.com/miru-zero/zero-brain

Made for: Claude Code, Codex.

Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,519 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin 98% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00053 $0.03519
Opus 5 $0.00026 $0.01759
Sonnet 5 $0.00011 $0.00704
Haiku 4.5 $0.00005 $0.00352

Measured yesterday against content hash e84de464e204, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

macos-process-injection scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

"require('child_process').execSync('id').toString()"
Origin

This is a copy

98% identical to macos-process-injection — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/macos-process-injection/SKILL.md · 385 lines

How it starts

The opening of the file, as written. The whole thing — 385 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: macOS Process Injection — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert macOS process injection techniques. Covers DYLD_INSERT_LIBRARIES, dylib hijacking (weak/rpath/proxy), XPC PID reuse attacks, Mach port manipulation, MIG abuse, and Electron injection. Base models miss entitlement prerequisites and SIP constraints on injection vectors.

Before going deep, consider loading:

Advanced Reference

Also load DYLIB_XPC_TECHNIQUES.md when you need:

  • Step-by-step dylib hijacking methodology with tooling commands
  • XPC exploitation walkthrough with code examples
  • Mach port technique details and task_for_pid patterns

1. DYLD_INSERT_LIBRARIES INJECTION

The most straightforward injection: set an environment variable that forces the dynamic linker to preload your dylib.

1.1 Requirements and Restrictions

Condition Can Inject? Reason
Normal (non-hardened) binary Yes No restrictions
Hardened Runtime enabled No DYLD strips env vars
Hardened Runtime + com.apple.security.cs.allow-dyld-environment-variables Yes Entitlement explicitly allows it
Apple system binary (SIP-protected) No DYLD env vars stripped by SIP
SUID/SGID binary No DYLD env vars stripped for privilege safety
App Sandbox enabled No Sandbox blocks env var injection

1.2 Basic Injection

# Create malicious dylib
cat > inject.c << 'EOF'
#include <stdio.h>
__attribute__((constructor))
void inject() {
    printf("[+] Injected into PID %d\n", getpid());
    // payload here
}
EOF

# Compile for both architectures
gcc -dynamiclib -o inject.dylib inject.c -arch x86_64 -arch arm64

# Inject into target
DYLD_INSERT_LIBRARIES=./inject.dylib /path/to/target

Read the full file on GitHub · 385 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 385 lines · 53 tokens per session scan A e84de464e204

Subscribe to this mod's changes

macos-process-injection is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 14d ago), licensed MIT. It adds 53 tokens to every session and 3,519 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). It is 98% identical to macos-process-injection, differing in 4 lines, and is treated as a copy.

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