Angular security

Security

Priority: P0 (CRITICAL)

Principles

• XSS Prevention: Angular sanitizes interpolated values by default — {{ userInput }} is safe. Do NOT use innerHTML unless absolutely necessary (e.g., trusted static CMS content). For user-generated content, display as text with {{ content }} — never as HTML.
• Bypass Security: Only bypass security for content you control (e.g., trusted CMS headers). Never call bypassSecurityTrustHtml on user-provided data. Use DomSanitizer.sanitize(SecurityContext.HTML, content) instead of bypass functions. Audit every bypassSecurityTrust* call as a potential XSS vector.
• Route Guards: Protect all sensitive routes with a functional CanActivateFn (e.g., inject(Router).createUrlTree(['/login'])). Apply with canActivate: [authGuard].

Guidelines

• CSP: Configure CSP headers on the 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 the server — not localStorage or sessionStorage because they are accessible via XSS.
• Secrets: Never store API keys or secrets in Angular source code or bundle.

Anti-Patterns

• No bypassSecurityTrust: Trust Angular's sanitization; bypass only for verified static content.
• 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