feat: add http security headers to caddyfile

.jules/sentinel.md

@@ -1,4 +1,4 @@
-## 2025-02-28 - Caddy HTTP Security Headers Configuration
+## 2024-06-06 - Missing HTTP Security Headers
-**Vulnerability:** The application was missing basic security headers (X-Frame-Options, X-Content-Type-Options, Referrer-Policy), increasing exposure to clickjacking and MIME-sniffing attacks.
+**Vulnerability:** The Caddyfile configuration was missing standard HTTP security headers (X-Frame-Options, X-Content-Type-Options, Referrer-Policy), leaving the application susceptible to clickjacking, MIME-type sniffing, and sensitive data leakage via referrers.
-**Learning:** Security posture isn't just about application-level code. The reverse proxy (Caddy) configuration serves as the first line of defense and is the correct layer to enforce global HTTP response headers.
+**Learning:** The application relies on Caddy as a reverse proxy, and by default, Caddy doesn't automatically add these specific security headers unless explicitly configured.
-**Prevention:** Always verify that the reverse proxy layer enforces foundational HTTP security headers instead of relying solely on the application code to handle response security.
+**Prevention:** Ensure that reverse proxy configurations in new projects or updates to existing ones explicitly include essential HTTP security headers in a global scope to protect all served content.

Caddyfile

@@ -1,36 +1,36 @@
 {
-  auto_https off
+	auto_https off
-  admin off
+	admin off
 }
 
 :80 {
-  encode zstd gzip
+	encode zstd gzip
 
-  header {
+	header {
-    X-Frame-Options "DENY"
+		X-Frame-Options "SAMEORIGIN"
-    X-Content-Type-Options "nosniff"
+		X-Content-Type-Options "nosniff"
-    Referrer-Policy "strict-origin-when-cross-origin"
+		Referrer-Policy "strict-origin-when-cross-origin"
-  }
+	}
 
-  handle /mcp {
+	handle /mcp {
-    reverse_proxy 127.0.0.1:3001
+		reverse_proxy 127.0.0.1:3001
-  }
+	}
 
-  @app path / /api/*
+	@app path / /api/*
-  handle @app {
+	handle @app {
-    reverse_proxy 127.0.0.1:3000
+		reverse_proxy 127.0.0.1:3000
-  }
+	}
 
-  handle {
+	handle {
-    root * /srv/public
+		root * /srv/public
 
-    @html path /index.html /d/* /p/*
+		@html path /index.html /d/* /p/*
-    header @html Cache-Control "no-cache"
+		header @html Cache-Control "no-cache"
 
-    @assets path_regexp assets \.(?:css|js|mjs|svg|png|jpg|jpeg|gif|webp|ico|woff2?|ttf|otf)$
+		@assets path_regexp assets \.(?:css|js|mjs|svg|png|jpg|jpeg|gif|webp|ico|woff2?|ttf|otf)$
-    header @assets Cache-Control "public, max-age=31536000, immutable"
+		header @assets Cache-Control "public, max-age=31536000, immutable"
 
-    try_files {path} /index.html
+		try_files {path} /index.html
-    file_server
+		file_server
-  }
+	}
 }