Performing Security Headers Audit

When to Use

• During authorized web application security assessments as a standard configuration review
• When evaluating browser-level protections against XSS, clickjacking, and data leakage
• For compliance assessments requiring security header implementation (PCI DSS, SOC 2)
• When performing initial reconnaissance to identify easy-win security improvements
• During CI/CD pipeline security gate checks for new deployments

Prerequisites

• Authorization: Written scope for the target application (header review is low-risk)
• curl: For fetching response headers from target endpoints
• SecurityHeaders.com: Online scanner for quick header assessment
• Mozilla Observatory: Mozilla's web security testing tool
• Burp Suite: For comprehensive header analysis across multiple pages
• Browser DevTools: For examining headers and CSP violations in real-time

Workflow

Step 1: Collect Security Headers from Target

Retrieve and catalog all security-related response headers.

# Fetch all response headers
curl -s -I "https://target.example.com/" | grep -iE \
  "(strict-transport|content-security|x-frame|x-content-type|x-xss|referrer-policy|permissions-policy|feature-policy|x-permitted|cross-origin|set-cookie|server|x-powered-by|cache-control)"

# Check headers across multiple pages
PAGES=("/" "/login" "/api/health" "/admin" "/account/settings" "/static/app.js")

for page in "${PAGES[@]}"; do
  echo "=== $page ==="
  curl -s -I "https://target.example.com$page" 2>/dev/null | grep -iE \
    "(strict-transport|content-security|x-frame|x-content-type|x-xss|referrer-policy|permissions-policy|set-cookie|server|x-powered)"
  echo
done

# Check both HTTP and HTTPS responses
echo "=== HTTP Response ==="
curl -s -I "http://target.example.com/" | head -20
echo "=== HTTPS Response ==="
curl -s -I "https://target.example.com/" | head -20

Step 2: Assess Transport Security (HSTS)

Evaluate HTTP Strict Transport Security configuration.

# Check HSTS header
curl -s -I "https://target.example.com/" | grep -i "strict-transport-security"

# Expected: Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

# Verify HSTS attributes:
# max-age: Should be >= 31536000 (1 year) for preload eligibility
# includeSubDomains: Protects all subdomains
# preload: Eligible for browser HSTS preload list

# Check if HTTP redirects to HTTPS
curl -s -I "http://target.example.com/" | head -5
# Should be 301/302 redirect to https://

# Check if HSTS is on the preload list
# Visit: https://hstspreload.org/?domain=target.example.com

# Test for HTTPS-only cookies
curl -s -I "https://target.example.com/login" | grep -i "set-cookie"
# All session cookies should have Secure flag

# Check for mixed content
curl -s "https://target.example.com/" | grep -oP "http://[^\"']+" | head -20
# HTTP resources loaded on HTTPS pages create mixed content vulnerabilities

Step 3: Audit Content Security Policy (CSP)

Analyze CSP headers for effectiveness and potential bypasses.

# Extract CSP header
CSP=$(curl -s -I "https://target.example.com/" | grep -i "content-security-policy" | cut -d: -f2-)
echo "$CSP"

# Check for dangerous directives:
# 'unsafe-inline' in script-src: Allows inline scripts (XSS risk)
# 'unsafe-eval' in script-src: Allows eval() (XSS risk)
# * in any directive: Allows loading from any origin
# data: in script-src: Allows data: URI scripts
# Missing default-src: No fallback policy

echo "$CSP" | tr ';' '\n' | while read directive; do
  echo "  $directive"
  if echo "$directive" | grep -q "unsafe-inline"; then
    echo "    WARNING: unsafe-inline allows inline script execution"
  fi
  if echo "$directive" | grep -q "unsafe-eval"; then
    echo "    WARNING: unsafe-eval allows eval() calls"
  fi
  if echo "$directive" | grep -q " \* "; then
    echo "    WARNING: wildcard allows loading from any origin"
  fi
done

# Check for CSP report-only (not enforcing)
curl -s -I "https://target.example.com/" | grep -i "content-security-policy-report-only"
# Report-only does NOT block violations, only logs them

# Test CSP with Google's evaluator
# https://csp-evaluator.withgoogle.com/
# Paste the CSP header for automated analysis

# Check for CSP bypass via whitelisted domains
# If CDN domains are whitelisted, check for JSONP endpoints or angular libraries

Step 4: Check Frame Protection and Click Defense Headers

…