Privilege Escalation in Echo Go with Basic Auth

In Echo Go, using HTTP Basic Authentication in combination with role-based access controls can lead to privilege escalation when role or permission checks are incomplete or applied inconsistently after authentication. Basic Auth is a simple mechanism where the client sends an Authorization: Basic base64(credentials) header; if the server decodes this and maps the username to a role or group without enforcing authorization on each sensitive handler, an authenticated low-privilege user may be able to reach admin-only endpoints.

Consider an Echo Go service that authenticates via Basic Auth and then relies on a lightweight role claim stored in the context. If routes for user management or configuration are protected only by authentication middleware and not by explicit authorization checks, a user who can change their own username or group assignment (or whose group mapping is derived from an attacker-controlled source) may escalate to an admin role. This becomes more likely when the application reuses usernames across environments or when group membership is embedded in the username (e.g., user:admin) and parsed naively by the server.

Another scenario involves IDOR-like paths where an authenticated user can modify another user’s role attribute in a shared datastore, then access admin-only resources on subsequent requests. Since Basic Auth credentials are sent with every request, an attacker who compromises a low-privilege account might leverage weak authorization logic to invoke admin routes. Echo Go handlers that inspect context for a role but fail to validate it against a server-side, tamper-proof source (such as a verified JWT with role claims or a server-managed session mapping) are vulnerable.

Additionally, if the service exposes an OpenAPI spec and the spec incorrectly marks admin routes as requiring only authentication (and not a specific role), runtime behavior may diverge from documentation. An attacker using an API scanner like middleBrick can detect these inconsistencies by comparing the spec’s security requirements with actual responses, identifying endpoints where authentication alone grants access that should require elevated privileges.

Common root causes include missing role checks on sensitive routes, incorrect group extraction from the Basic Auth identity, and over-permissive wildcard middleware. To detect such issues, tools that test unauthenticated and authenticated surfaces—such as middleBrick, which runs 12 security checks including BOLA/IDOR and Privilege Escalation—can surface discrepancies between documented security schemes and actual enforcement in Echo Go services.

Remediate privilege escalation risks in Echo Go by enforcing strict authorization after authentication, avoiding role derivation from untrusted sources, and validating permissions on every sensitive handler. Below are concrete, working examples.

Example 1: Basic Auth with explicit role enforcement

Use middleware to authenticate via Basic Auth, then enforce role-based access on admin routes rather than relying on authentication alone.

package main

import (
	"encoding/base64"
	"net/http"
	"strings"

	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
)

type userRole string

const (
	roleAdmin userRole = "admin"
	roleUser  userRole = "user"
)

// parseBasicAuth extracts username and role from Basic Auth credentials.
// In production, roles should be sourced from a trusted store (e.g., DB or verified claims).
func parseBasicAuth(auth string) (string, userRole, error) {
	parts := strings.SplitN(auth, ":", 2)
	if len(parts) != 2 {
		return "", "", http.ErrMissingHeader
	}
	username := parts[0]
	// Example mapping; in real services, look up role from a verified source.
	var role userRole
	if username == "admin" {
		role = roleAdmin
	} else {
		role = roleUser
	}
	return username, role, nil
}

func basicAuthMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
	return func(c echo.Context) error {
		auth := c.Request().Header.Get("Authorization")
		if auth == "" || !strings.HasPrefix(auth, "Basic ") {
			return c.String(http.StatusUnauthorized, "Unauthorized")
		}
		payload, err := base64.StdEncoding.DecodeString(auth[7:])
		if err != nil {
			return c.String(http.StatusUnauthorized, "Invalid authorization header")
		}
		username, role, err := parseBasicAuth(string(payload))
		if err != nil {
			return c.String(http.StatusUnauthorized, "Invalid credentials")
		}
		// Attach verified role to context for downstream handlers.
		c.Set("user", username)
		c.Set("role", role)
		return next(c)
	}
}

func adminOnly(next echo.HandlerFunc) echo.HandlerFunc {
	return func(c echo.Context) error {
		role, ok := c.Get("role").(userRole)
		if !ok || role != roleAdmin {
			return c.String(http.StatusForbidden, "Insufficient permissions")
		}
		return next(c)
	}
}

func main() {
	e := echo.New()
	e.Use(basicAuthMiddleware)

	e.GET("/public", func(c echo.Context) error {
		return c.String(http.StatusOK, "Public endpoint")
	})

	e.GET("/admin/dashboard", adminOnly, func(c echo.Context) error {
		return c.String(http.StatusOK, "Admin dashboard")
	})

	e.Logger.Fatal(e.Start(":8080"))
}

Example 2: Role verification from a trusted source

For stronger security, avoid deriving roles from the username string. Instead, validate permissions using server-side data and ensure role checks are applied to all sensitive operations.

package main

import (
	"net/http"

	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
)

var roleByUser = map[string]string{
	"alice": "admin",
	"bob":   "user",
}

func verifyRole(required string) echo.MiddlewareFunc {
	return func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) error {
			user, ok := c.Get("user").(string)
			if !ok {
				return c.String(http.StatusUnauthorized, "Unauthorized")
			}
			role, exists := roleByUser[user]
			if !exists || role != required {
				return c.String(http.StatusForbidden, "Insufficient permissions")
			}
			return next(c)
		}
	}
}

func main() {
	e := echo.New()
	e.Use(middleware.BasicAuth(func(username, password string, c echo.Context) (bool, error) {
		// Validate password against a secure store; simplified here.
		return password == "secret", nil
	}))

	e.GET("/users/:id", func(c echo.Context) error {
		c.Set("user", c.Param("id"))
		return c.String(http.StatusOK, "User profile")
	})

	e.POST("/users/:id/promote", verifyRole("admin"), func(c echo.Context) error {
		// Only admins can reach this handler.
		return c.NoContent(http.StatusNoContent)
	})

	e.Logger.Fatal(e.Start(":8080"))
}

Additional measures include avoiding the use of usernames to encode roles, validating permissions server-side on every request, and auditing your authorization logic against frameworks like OWASP API Security Top 10 and relevant compliance controls. middleBrick can help surface authorization inconsistencies in your API surface by comparing spec-defined security schemes against runtime behavior.