Security

Priority: P0 (CRITICAL)

Principles

• XSS Prevention: Angular sanitizes interpolated values by default — {{ userInput }} safe. NOT use innerHTML unless absolutely necessary (e.g., trusted static CMS content). For user-generated content, display as text with {{ content }} — never as HTML.
• Trusted HTML APIs: Mark HTML as trusted only for content you control (e.g., vetted CMS headers). Never mark user-provided data as trusted. Prefer DomSanitizer.sanitize(SecurityContext.HTML, content) and review every trust-marking call as a potential XSS vector.
• Route Guards: Protect all sensitive routes with functional CanActivateFn (e.g., inject(Router).createUrlTree(['/login'])). Apply with canActivate: [authGuard].

Guidelines

• CSP: Configure CSP headers on server (not in Angular source). Use nonce-based CSP with script-src 'nonce-{nonce}' and avoid unsafe-inline/unsafe-eval.
• HTTP: Use Interceptors to attach secure tokens. Use HttpOnly cookies managed by server — not localStorage or sessionStorage because they accessible via XSS.
• Secrets: Never store API keys or secrets in Angular source code or bundle.

Anti-Patterns

• No trust-marking on user input: Trust Angular's sanitization; reserve trusted HTML APIs for verified static content only.
• No localStorage for tokens: Use HttpOnly cookies via interceptors for auth tokens.
• No secrets in source: Never embed API keys or secrets in Angular bundle code.

References

• Security Best Practices
• common/security-standards