Homebrew is a package manager for macOS. The post here aim to provide basic guidance for how to examines Homebrew’s security model, identifies potential risks, and provides security best practices.

Understanding the Trust Chain

When you install a package with Homebrew, you’re trusting several parties:

  • Homebrew maintainers — Review and approve package formulas
  • Package contributors — Write the installation recipes
  • Original software authors — Create the actual software
  • Download sources — Host the software files

How Homebrew Stays Safe

Package Review Process

Homebrew has a review process for all packages:

  • Source verification — Validates download URLs and checksums
  • Build process review — Examines installation steps
  • Security screening — Identifies potential vulnerabilities
  • Community oversight — Multiple reviewers check each formula

Checksum Verification

Every Homebrew package includes checksums to ensure file integrity:

# Source:
# - https://github.com/Homebrew/homebrew-core/blob/master/Formula/w/wget.rb
class Wget < Formula
  url "https://ftpmirror.gnu.org/gnu/wget/wget-1.25.0.tar.gz"
  sha256 "766e48423e79359ea31e41db9e5c289675947a7fcf2efdcedb726ac9d0da3784"
  # ...
end

Sandboxed Building

Homebrew compiles software in a controlled environment:

  • Limited system access — Prevents modification of critical files
  • Isolated build process — Each package builds separately
  • Predictable environment — Consistent build conditions

Potential Security Risks

Supply Chain Attacks

  • Compromised upstream sources — Original software repositories get hacked
  • Malicious formulas — Bad actors submit harmful installation recipes
  • Dependency confusion — Fake packages with similar names to legitimate ones

Network-Based Threats

  • Man-in-the-middle attacks (MITM) — Intercepted downloads on unsecured networks
  • DNS hijacking — Redirected downloads to malicious servers
  • Certificate issues — Compromised or invalid SSL certificates

Local System Risks

  • Privilege escalation — Software attempting to gain admin access
  • Persistent malware — Programs that remain after installation
  • Data access — Applications accessing sensitive user files

Security Best Practices

1. Never use sudo with Homebrew

Homebrew is designed to work without administrator privileges:

# ❌ DON'T do this
sudo brew install "${PACKAGE}"

# ✅ DO this instead
brew install "${PACKAGE}"

2. Research Packages Before Installing

Investigate unfamiliar packages:

# View package details
brew info "${PACKAGE}"

# Check dependencies for potential risks
brew deps "${PACKAGE}"

# Scan for formula issues
brew audit "${PACKAGE}"

3. Prefer Official Sources

  • Use homebrew/core — The main repository with comprehensive review
  • Exercise caution with third-party taps — Less oversight than core
  • Review formulas on GitHub — Inspect installation code before use

4. Keep Everything Updated

Updates include patches:

# Check your current Homebrew version
brew --version

# Update Homebrew itself
brew update

# Update all packages
brew upgrade

# Update specific package
brew upgrade "${PACKAGE}"

Detecting outdated versions:

  • Homebrew displays update reminders during command execution
  • Compare your version with latest releases
  • brew doctor warns about outdated versions

Older versions may contain potential issues. Maintain current versions for patches and improved sandboxing.

5. Use Secure Networks

  • Avoid public internet for package installations
  • Use VPN when on untrusted networks
  • Verify HTTPS/Certificates — Homebrew uses encrypted downloads

6. Monitor and Verify Your Installation

Monitor installed packages:

# Check Homebrew version
brew --version

# Show installed packages
brew list

# Check for outdated packages
brew outdated

# Diagnose potential issues
brew doctor

For suspicious packages:

  • Compare checksums with official sources
  • Report anomalies to the Homebrew community
  • Remove suspicious packages immediately

Homebrew Cask Security

Homebrew Cask installs pre-built macOS applications with different security implications:

Key Differences from Regular Homebrew

  • Pre-compiled binaries — Downloaded as-is, not built from source
  • Less community review — Fewer eyes examining the software
  • System permissions — Apps may request admin access
  • Code signing varies — Not all apps are properly signed

Cask Safety Tips

# Research cask before installing
brew info --cask "${APP}"

# Verify app signatures
codesign --display --verbose=9 "/Applications/${APP}.app"

Security Assessment

Homebrew balances convenience with security:

Homebrew’s Strengths

  • Community oversight — Distributed code review
  • Transparent process — Public formulas on GitHub
  • Security updates — Responsive vulnerability patching
  • Sandboxed builds — Restricted system access

Inherent Limitations

  • Trust-based system — Relies on community vigilance
  • Supply chain risks — Vulnerabilities in upstream sources
  • User responsibility — Requires following best practices

Key Takeaways

  1. Homebrew provides reasonable security with proper precautions
  2. Avoid sudo — it compromises Homebrew’s security model
  3. Research packages before installation, especially unfamiliar ones
  4. Maintain current versions for patches (including brew itself)
  5. Monitor installations and verify suspicious packages

Security Resources