Macos Security Hardening

macOS Security & Privilege Escalation

A comprehensive guide for assessing and understanding macOS security mechanisms, privilege escalation vectors, and hardening techniques.

Quick Start

When assessing a macOS system, follow this workflow:

1. Gather system information - Version, architecture, users
2. Check security protections - SIP, TCC status
3. Enumerate attack surface - File permissions, services, installed apps
4. Identify privilege escalation vectors - SUID binaries, writable files, TCC abuse
5. Document findings - Create a structured report

macOS Security Architecture

Core Concepts

macOS security relies on several layered protections:

• SIP (System Integrity Protection): Protects system files and processes from modification, even by root
• TCC (Transparency, Consent, and Control): Controls app access to sensitive data (microphone, camera, files, etc.)
• Code Signing: Apps must be signed to run; unsigned apps are blocked or require user approval
• Gatekeeper: Verifies app signatures and quarantine status
• AMFI (Apple Mobile File Integrity): Enforces code signing at the kernel level

Check SIP Status

# Check if SIP is enabled
csrutil status

# From within macOS (requires reboot to change)
# If disabled, you can modify system files

Check TCC Database

# List TCC database entries
sqlite3 /Library/Application\ Support/com.apple.TCC/TCC.db "SELECT * FROM access;"

# Check specific app permissions
sqlite3 /Library/Application\ Support/com.apple.TCC/TCC.db "SELECT * FROM access WHERE client LIKE '%app_name%';"

Attack Surface Enumeration

File Permission Vulnerabilities

Root-owned processes writing to user-controllable files create privilege escalation opportunities:

# Find world-writable files in system directories
find /usr /System /Library -perm -0002 -type f 2>/dev/null

# Find files owned by root but writable by group
find /usr /System /Library -user root -group wheel -perm -0020 -type f 2>/dev/null

# Find SUID/SGID binaries
find / -perm -4000 -type f 2>/dev/null  # SUID
find / -perm -2000 -type f 2>/dev/null  # SGID

# Check for writable directories in system paths
find /usr /System /Library -perm -0002 -type d 2>/dev/null

Check for Vulnerable Installers

# List installed packages
pkgutil --pkgs

# Check package receipts for vulnerabilities
pkgutil --pkg-info <package_id>

# Look for .pkg files that might be reinstalled
find / -name "*.pkg" -type f 2>/dev/null

File Extension & URL Scheme Handlers

# Check registered file type handlers
defaults read com.apple.LaunchServices/com.apple.launchservices.secure

# Check URL scheme handlers
mdls -name kMDItemCFBundleIdentifier -name kMDItemContentType /Applications/*.app

# List all registered apps
/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -dump

TCC Privilege Escalation

Understanding TCC

TCC controls access to:

• Microphone, camera, screen recording
• Accessibility features
• File system areas (Documents, Downloads, etc.)
• Contacts, calendar, reminders
• System preferences

TCC Bypass Techniques

1. Inherit from privileged parent: Child processes inherit TCC permissions from parent
2. Abuse signed apps: Use entitlements from signed applications
3. Database manipulation: Modify TCC.db directly (requires SIP disabled)
4. Accessibility API abuse: Use accessibility permissions to control other apps

Check TCC Permissions

# List all TCC permissions
tccutil list

# Check specific permission categories
tccutil reset All <app_bundle_id>

SIP Bypass Considerations

When SIP is Disabled

If SIP is disabled, you can:

• Modify system binaries
• Load unsigned kernel extensions
• Access protected system files
• Modify TCC database directly

Common SIP Bypass Vectors

Historical bypasses have exploited:

• Kernel vulnerabilities
• Code signing bypasses
• System call injection
• Memory corruption in system processes

Note: Modern macOS versions have significantly hardened against these attacks. Always check for the latest CVEs and patches.

Traditional Privilege Escalation

SUID/SGID Binary Abuse

# Find SUID binaries and check for known exploits
find / -perm -4000 -type f 2>/dev/null | while read bin; do
    echo "=== $bin ==="
    which $bin 2>/dev/null || echo "Not in PATH"
done

Cron Jobs & LaunchDaemons

# Check user cron jobs
cat /etc/crontab
cat /etc/cron.d/*
ls -la /etc/cron.*

# Check LaunchDaemons (system services)
ls -la /Library/LaunchDaemons/
ls -la /System/Library/LaunchDaemons/

# Check LaunchAgents (user services)
ls -la ~/Library/LaunchAgents/
ls -la /Library/LaunchAgents/

Writable System Files

# Find files writable by current user in system directories
find /usr /System /Library -writable -type f 2>/dev/null

# Check for PATH injection opportunities
find /usr/local/bin /usr/bin /bin -writable -type d 2>/dev/null

Security Hardening Recommendations

Disable Unnecessary Services

# List all running services
launchctl list

# Disable a service
launchctl bootout system/<service_label>

Enable Full Disk Encryption

# Check FileVault status
fdesetup status

# Enable FileVault
sudo fdesetup enable

Configure Firewall

# Check firewall status
/usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate

# Enable firewall
sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on

Audit User Accounts

# List all users
df -H

# Check for accounts with sudo privileges
grep -i sudo /etc/sudoers
grep -i sudo /etc/sudoers.d/*

# Check last login times
last

Compliance & Standards

NIST macOS Security Baseline

Reference: https://github.com/usnistgov/macos_security

Key controls:

• Password policies
• Account management
• Audit logging
• File integrity monitoring
• Network security

CIS Benchmarks

Follow CIS macOS Benchmark for comprehensive hardening guidance.

Practical Assessment Workflow

Step 1: Initial Reconnaissance

# System information
sw_vers
uname -a

# Current user and groups
whoami
groups
id

# Check if root
sudo -l

Step 2: Security Status Check

# SIP status (requires reboot to check properly)
csrutil status

# TCC permissions
tccutil list

# FileVault
fdesetup status

# Firewall
/usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate

Step 3: Attack Surface Scan

# Run the enumeration commands from above
# Document all findings

Step 4: Exploitation Testing

# Test each identified vector
# Document success/failure
# Note any limitations

Reporting Template

# macOS Security Assessment Report

## System Information
- macOS Version: 
- Architecture: 
- Current User: 

## Security Protections
- SIP: [Enabled/Disabled]
- TCC: [Status]
- FileVault: [Enabled/Disabled]
- Firewall: [Enabled/Disabled]

## Findings

### Critical
- [List critical vulnerabilities]

### High
- [List high-severity issues]

### Medium
- [List medium-severity issues]

### Low
- [List low-severity issues]

## Recommendations
- [Prioritized remediation steps]

References

• NIST macOS Security
• Apple Open Source
• OS X Incident Response
• TAOMM macOS Analysis

Important Notes

1. Legal Authorization: Only perform security assessments on systems you own or have explicit authorization to test.

2. Backup First: Always backup systems before making security changes.

3. Test in Isolation: Test privilege escalation techniques in isolated environments first.

4. Stay Updated: macOS security evolves rapidly. Check for the latest CVEs and patches.

5. Documentation: Document all findings and changes for audit purposes.