OffensiveCon26 - Design-Based Vulnerabilities on macOS: Oops, Not a One-Shot Fix

Design-Based macOS Vulnerabilities

Independent researcher Zhongquan Li presents design flaws discovered between 2024 and 2025, noting Apple can take years to patch such issues. He contrasts memory-corruption bugs with design weaknesses where finding the attack surface is often harder than exploitation.

TCC, SIP, and Root Limitations

On macOS, userland root is not equivalent to full control: sandboxed app data requires Transparency, Consent, and Control (TCC) permissions. System Integrity Protection (SIP) blocks persistence and unsigned kernel extensions. Li explains why Pwn2Own rarely accepts standalone userland root.

Package Installer Attack Chain

Malicious .pkg installers run attacker-controlled pre-install and post-install scripts via package_script_service, which holds powerful entitlements including data-vault access. A demo drops a persistent SUID binary under /Library/InstallerSandboxes that even root with Full Disk Access cannot delete.

Abusing Extended Attributes for TCC Bypass

Chaining package-script privileges with Estero extended-attribute manipulation lets an attacker modify TCC-protected content in installer sandbox paths, enabling remote TCC bypass and persistence without trivial one-shot fixes.