Hacking My Own Mac App: Penetration Testing macOS Defense Boundaries in a VM

A Japanese version of this is on Zenn . I build and sell a macOS network-security menu bar app called RoamSwitch . In a previous post , I wrote about attacking my own Mac from an Arch Linux box on the same LAN to see how it handled basic reconnaissance and rogue device probes. Since then, as I kept adding features and refactoring, a nagging question kept resurfacing: Are we introducing regressions? Is our privileged helper still watertight? Did a recent update accidentally punch a hole in our packet filter rules? Manually poking at firewalls on every release is tedious and risky—messing with Packet Filter ( pf ) and root LaunchDaemons on your primary dev machine is a great way to accidentally drop your own network connection. So, to be absolutely thorough, I set up a repeatable, automated pentest suite inside a disposable macOS virtual machine on a Mac (using Tart ) to rigorously probe all 5 defense boundaries from the outside. Here is how the test harness works and what the logs showed when I attacked it. Test Architecture: Host Mac ⇄ Target Guest VM Running destructive firewall tests or killing root helpers on your daily driver is stressful. Instead, I used Tart , a lightweight macOS virtualization tool, to spin up a clean macOS Sonoma guest VM as the Target , with the Host machine acting as the Attacker . +------------------------------------+ +-----------------------------------------+ | Host Mac (Attacker) | | macOS VM (Target Guest) | | - Inbound Port Probing (nc/nmap) | -----> | - RoamSwitch 1.4.8 (Defense Engine) | | - Unauthorized HTTP Probing (curl)| Virtual | - Root Privileged Helper | | - Rogue ARP Spoofing (scapy) | Bridge | - Packet Filter (pf) Ruleset Anchor | +------------------------------------+ +-----------------------------------------+ The 5 Defense Boundaries Tested graph TD A[Automated Defense Suite] --> B[1. XPC Authorization Boundary (§3)] A --> C[2. pf Ruleset & Air-Gap Precedence (§4, §5)] A --> D[3. Port Anomaly & Global Exposure (§6)] A