Vulnerable Components in Echo Go with Basic Auth

Using HTTP Basic Authentication in an Echo Go API introduces several components that, when combined, can expose the application to common security weaknesses. Echo Go is a popular HTTP request router and framework, and Basic Auth typically relies on the client sending an Authorization header with base64-encoded credentials in each request. The vulnerability surface arises when the handler logic does not properly validate credentials, enforce transport security, or scope authorization checks per request.

One specific risk is the absence of TLS. Basic Auth sends credentials in an easily decodable format; without HTTPS, credentials can be intercepted on the network. In Echo Go, if routes are defined without enforcing HTTPS via middleware, the API exposes credentials to passive eavesdropping. This maps directly to the Data Exposure checks performed by middleBrick, which flags cleartext transmission of sensitive data and references real-world attack patterns such as credential sniffing on shared networks.

A second component is the authorization check pattern. Developers sometimes authenticate a user once (e.g., via Basic Auth) but fail to enforce per-request or per-resource authorization. In Echo Go, this can occur when a middleware sets a user context but subsequent handlers do not validate whether that user is permitted to access the specific resource. This gap can lead to Insecure Direct Object References (IDOR) or Broken Object Level Authorization (BOLA), which are covered under middleBrick’s BOLA/IDOR checks. For example, an endpoint like /users/{id} might authenticate a user but not verify that the authenticated user owns the requested ID, allowing horizontal privilege escalation.

A third component is input validation around the Authorization header itself. Basic Auth credentials are often parsed by custom middleware. If the middleware does not strictly validate the format, reject malformed headers, or guard against brute-force attempts, the endpoint becomes susceptible to injection or enumeration attacks. Echo Go applications that log credentials inadvertently (for debugging) further risk Data Exposure. middleBrick’s Data Exposure and Input Validation checks detect these issues by analyzing the API specification and runtime behavior, identifying whether credentials are logged, whether error messages leak sensitive information, and whether rate limiting is insufficient to deter credential guessing.

Finally, the combination of unauthenticated endpoint discovery and Basic Auth can lead to an unauthenticated LLM endpoint scenario, which is a unique capability of middleBrick’s LLM/AI Security checks. If an API documentation or debugging route (such as /debug or an exposed OpenAPI spec) does not require authentication and returns information about the authentication mechanism or sample tokens, attackers can harvest data to refine credential-based attacks. middleBrick scans for such unauthenticated endpoints and tests for prompt injection or system prompt leakage where LLMs are used, even though in this case the exposure involves authentication metadata rather than model prompts.

Remediation focuses on secure transport, strict validation, and proper authorization checks. Below are concrete, working examples of Basic Auth implemented safely in Echo Go.

1. Enforce HTTPS and use secure middleware

Always serve APIs over TLS. In production, terminate TLS at the load balancer or reverse proxy, but also consider enforcing HTTPS in Echo Go middleware to reject cleartext HTTP requests.

// Enforce HTTPS in Echo Go
package main

import (
	"net/http"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
)

func main() {
	e := echo.New()
	// Redirect HTTP to HTTPS and enforce secure transport
	e.Use(middleware.ForceHTTPS())
	// Alternatively, use a custom middleware to reject HTTP in production
	e.Use(func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) error {
			if c.Request().TLS == nil {
				return c.String(http.StatusForbidden, "HTTPS required")
			}
			return next(c)
		}
	})
	e.StartTLS(":443", "cert.pem", "key.pem")
}

2. Validate and parse Basic Auth credentials securely

Use standardized middleware or carefully validate the Authorization header. Avoid logging credentials and ensure constant-time comparison to mitigate timing attacks.

// Basic Auth middleware with validation in Echo Go
package main

import (
	"crypto/subtle"
	"encoding/base64"
	"net/http"
	"strings"
	"github.com/labstack/echo/v4"
)

func BasicAuthMiddleware(expectedUser, expectedPass string) echo.MiddlewareFunc {
	return func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) error {
			auth := c.Request().Header.Get("Authorization")
			if auth == "" {
				return c.String(http.StatusUnauthorized, "Authorization header missing")
			}
			const prefix = "Basic "
			if !strings.HasPrefix(auth, prefix) {
				return c.String(http.StatusUnauthorized, "Invalid authorization type")
			}
			payload, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
			if err != nil {
				return c.String(http.StatusBadRequest, "Invalid authorization header")
			}
			parts := strings.SplitN(string(payload), ":", 2)
			if len(parts) != 2 {
				return c.String(http.StatusBadRequest, "Invalid credentials format")
			}
			user, pass := parts[0], parts[1]
			// Constant-time comparison to avoid timing attacks
			if subtle.ConstantTimeCompare([]byte(user), []byte(expectedUser)) != 1 ||
			   subtle.ConstantTimeCompare([]byte(pass), []byte(expectedPass)) != 1 {
				return c.String(http.StatusUnauthorized, "Invalid credentials")
			}
			// Set user context only after successful validation
			c.Set("user", user)
			return next(c)
		}
	}
}

// Usage in route definition
func userHandler(c echo.Context) error {
	user := c.Get("user").(string)
	return c.JSON(http.StatusOK, map[string]string{"hello": user})
}

func main() {
	e := echo.New()
	e.Use(BasicAuthMiddleware("admin", "S3cur3P@ss!"))
	e.GET("/profile", userHandler)
	e.Logger.Fatal(e.StartTLS(":443", "cert.pem", "key.pem"))
}

3. Scope authorization per request

After authentication, ensure handlers validate that the authenticated subject has permission for the specific resource. Combine Basic Auth with an authorization middleware or per-handler checks to prevent IDOR/BOLA.

// Example per-request ownership check in Echo Go
package main

import (
	"net/http"
	"strconv"
	"github.com/labstack/echo/v4"
)

// Assume user context is set after Basic Auth
func dataHandler(c echo.Context) error {
	user := c.Get("user").(string)
	idParam := c.Param("id")
	id, err := strconv.Atoi(idParam)
	if err != nil {
		return c.String(http.StatusBadRequest, "Invalid resource ID")
	}
	// Simulated lookup: in practice, query your database
	owner, err := lookupResourceOwner(id)
	if err != nil || owner != user {
		return c.String(http.StatusForbidden, "Access to this resource denied")
	}
	return c.JSON(http.StatusOK, map[string]string{"data": "safe payload"})
}

func lookupResourceOwner(id int) (string, error) {
	// Placeholder: implement actual data access logic
	return "admin", nil
}

4. Avoid logging credentials and enforce rate limiting

Ensure your middleware or logging does not capture Authorization headers. Use rate limiting to reduce brute-force risk. middleBrick’s Rate Limiting and Input Validation checks can verify these protections are present.

// Example: safe logging that excludes Authorization header
func safeLoggingMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
	return func(c echo.Context) error {
		// Log only method, path, and status; exclude headers with credentials
		c.Response().Header().Del(echo.HeaderAuthorization)
		return next(c)
	}
}