365devnet/SECURITY_REVIEW_CSP_CHANGES.md

Security Review: CSP and Cross-Origin Headers Changes

Changes Made

1. CSP default-src Directive

Change: Added explicit https://chat.365devnet.eu to default-src alongside existing https://*.365devnet.eu

Security Impact: ✅ SAFE - No security degradation

• The subdomain chat.365devnet.eu is already explicitly allowed in:
  • script-src (for RocketChat scripts)
  • connect-src (for API calls)
  • frame-src (for iframe embedding)
• The wildcard https://*.365devnet.eu should have covered it, but explicit entry ensures Windows browser compatibility
• This is a subdomain you control, not a third-party domain
• No new attack surface introduced

2. Cross-Origin-Resource-Policy Header

Change: Added Cross-Origin-Resource-Policy: same-site header

Security Impact: ✅ SECURITY ENHANCEMENT

• same-site restricts resource loading to pages from the same site (same eTLD+1)
• Since 365devnet.eu and chat.365devnet.eu share the same eTLD+1, they can still load each other's resources
• Prevents other websites from embedding your resources, which is a security improvement
• This is a defense-in-depth measure, not a weakening

Current Security Posture

✅ Strong Security Headers (All Present)

1. X-Content-Type-Options: nosniff - Prevents MIME type sniffing
2. Referrer-Policy: strict-origin-when-cross-origin - Limits referrer information leakage
3. Cross-Origin-Opener-Policy: same-origin - Prevents cross-origin window access
4. Cross-Origin-Embedder-Policy: credentialless - Isolates cross-origin resources
5. Cross-Origin-Resource-Policy: same-site - Prevents cross-site resource embedding (NEW)
6. Strict-Transport-Security - Enforces HTTPS with subdomain inclusion

⚠️ Known Acceptable Risks (Pre-existing)

1. CSP script-src with 'unsafe-inline'

Status: Acceptable risk, documented

• Required for inline scripts (RocketChat initialization, etc.)
• Documented in SECURITY_AUDIT.md as acceptable
• Could be improved with nonces in the future, but not critical

2. CSP script-src with 'wasm-unsafe-eval'

Status: Acceptable risk

• Required for WebAssembly execution
• Only allows WASM, not arbitrary eval()
• Necessary for modern web features

3. CSP img-src with https:

Status: Permissive but acceptable

• Allows images from any HTTPS source
• Common pattern for content-rich sites
• Could be restricted to specific domains if needed

4. CSP style-src with 'unsafe-inline'

Status: Standard practice

• Inline styles are common and generally safe
• Most sites use this pattern

🔒 CSP Directives Analysis

default-src 'self' https://365devnet.eu https://*.365devnet.eu https://chat.365devnet.eu;
// ✅ Restrictive - only allows own domains

script-src 'self' 'unsafe-inline' 'wasm-unsafe-eval' https://chat.365devnet.eu;
// ⚠️ Requires unsafe-inline (documented acceptable risk)

style-src 'self' 'unsafe-inline';
// ✅ Standard practice

img-src 'self' data: https: blob:;
// ⚠️ Permissive but acceptable for content sites

font-src 'self' data:;
// ✅ Restrictive - only self and data URIs

connect-src 'self' https://365devnet.eu https://*.365devnet.eu https://chat.365devnet.eu https://git.365devnet.eu wss://chat.365devnet.eu;
// ✅ Restrictive - only allows specific domains

frame-src 'self' https://chat.365devnet.eu;
// ✅ Restrictive - only allows RocketChat iframe

frame-ancestors 'none';
// ✅ Strong - prevents clickjacking

base-uri 'self';
// ✅ Strong - prevents base tag injection

form-action 'self';
// ✅ Strong - prevents form hijacking

Recommendations

✅ No Immediate Action Required

The changes made are secure and do not introduce vulnerabilities.

🔄 Future Improvements (Optional)

1. Consider nonces for inline scripts - Replace 'unsafe-inline' with nonce-based CSP
2. Restrict img-src - If possible, list specific image domains instead of https:
3. Add missing headers to nginx - For consistency, add Cross-Origin headers to nginx config (though they're already in server.js)

Conclusion

Security Status: ✅ SECURE

The changes made:

• ✅ Do not introduce new vulnerabilities
• ✅ Maintain existing security posture
• ✅ Add a security enhancement (Cross-Origin-Resource-Policy)
• ✅ Fix Windows compatibility without weakening security

The configuration remains secure and follows security best practices for a production website.