Cross Site Request Forgery in Echo Go with Basic Auth

Cross Site Request Forgery (CSRF) in the Echo Go framework combined with HTTP Basic Authentication creates a risk scenario where browser-based session credentials (the Authorization header) are automatically included by the client on every request to the same origin. Unlike cookie-based sessions, which can be protected with anti-CSRF tokens or SameSite attributes, Basic Auth credentials are often stored by the browser and sent automatically to the target host. If an authenticated user visits a malicious site while logged in to an Echo Go endpoint that relies solely on Basic Auth for authorization, the browser may send the credentials via a forged request (e.g., an image tag, form submission, or XMLHttpRequest). Because the server validates the Authorization header and does not require a per-session token or referrer/origin validation, the forged request can succeed, leading to unauthorized state changes.

Echo Go does not enforce any built-in CSRF protections for Basic Auth flows. Basic Auth is static and long-lived per credentials; if these credentials are leaked via a forged request, they remain valid until explicitly changed. Attackers can craft requests that leverage unsafe HTTP methods (POST, PUT, DELETE) to perform actions such as changing email, updating configuration, or initiating transfers. Even when Echo Go endpoints require authentication, the absence of CSRF-specific defenses like synchronizer tokens, custom headers, or strict CORS policies means that browser context alone can enable unauthorized actions. The scanner in middleBrick will flag missing CSRF protections and improper authentication schemes as security findings, noting that Basic Auth over HTTPS must be paired with additional safeguards to mitigate CSRF.

Consider an Echo Go handler that updates a user profile via a POST to /profile. If the route only checks for a valid Authorization header and does not validate the Origin header or require a CSRF token, a crafted form on a malicious site can submit changes on behalf of the authenticated user. middleBrick’s checks for BOLA/IDOR and authentication schemes help highlight that Basic Auth alone is insufficient for state-changing operations without CSRF controls. Since middleBrick scans the unauthenticated attack surface, it can detect whether endpoints that accept credentials also implement referrer checks, CORS restrictions, or anti-CSRF tokens, and surface these gaps with remediation guidance.

Remediation focuses on preventing unauthorized cross-origin requests while preserving the use of Basic Auth for transport-layer identification. The most robust approach is to avoid relying on Basic Auth as the sole authorization mechanism for state-changing operations and instead pair it with CSRF tokens or custom request headers that are not automatically sent by browsers. For safe integrations, use HTTPS to protect credentials in transit and implement strict CORS policies to limit origins and methods.

Example 1: Require a custom header (e.g., X-Requested-With) and validate Origin

package main

import (
    "net/http"
    "strings"

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

func isSafeRequest(r *http.Request) bool {
    // Require a custom header that browsers do not set automatically
    if r.Header.Get("X-Requested-With") != "XMLHttpRequest" {
        return false
    }
    // Optionally validate Origin or Referer for additional CSRF mitigation
    origin := r.Header.Get("Origin")
    if origin == "" {
        return true // allow non-browser clients
    }
    // Allowlist trusted origins
    allowed := map[string]bool{
        "https://your-trusted-app.com": true,
        "https://api.your-trusted-app.com": true,
    }
    return allowed[origin]
}

func updateProfile(c echo.Context) error {
    // Ensure credentials are present via Basic Auth
    user, pass, ok := c.Request().BasicAuth()
    if !ok || !isValidUserPass(user, pass) {
        return c.NoContent(http.StatusUnauthorized)
    }
    if !isSafeRequest(c.Request()) {
        return c.NoContent(http.StatusForbidden)
    }
    // Proceed with business logic
    return c.JSON(http.StatusOK, map[string]string{"status": "ok"})
}

func isValidUserPass(user, pass string) bool {
    // Validate against your user store
    return user == "admin" && pass == "securepass"
}

Example 2: Use middleware to enforce CSRF-safe methods and headers

package main

import (
    "net/http"

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

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

    // Enforce HTTPS in production (redirect when behind a proxy)
    e.Use(middleware.SecureWithConfig(middleware.SecureConfig{
        SSLRedirect: true,
    }))

    // Apply a CSRF-aware handler for state-changing routes
    e.POST("/profile", func(c echo.Context) error {
        user, pass, ok := c.Request().BasicAuth()
        if !ok || !isValidUserPass(user, pass) {
            return c.NoContent(http.StatusUnauthorized)
        }
        // Require a custom header to ensure same-origin request
        if c.Request().Header.Get("X-CSRF-Token") != "expected-token" {
            return c.NoContent(http.StatusForbidden)
        }
        return c.JSON(http.StatusOK, map[string]string{"result": "updated"})
    })

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

func isValidUserPass(user, pass string) bool {
    // Replace with secure credential validation
    return user == "admin" && pass == "complexsecret"
}

Recommendations

• Do not rely on Basic Auth alone for CSRF protection; combine it with custom headers (e.g., X-Requested-With, X-CSRF-Token) that are not automatically sent by browsers.
• Validate the Origin and Referer headers for same-site expectations on state-changing methods (POST, PUT, DELETE).
• Use short-lived credentials and rotate them regularly; avoid embedding credentials in JavaScript or client-side code.
• Leverage middleBrick scans to verify that endpoints requiring Basic Auth also implement referrer checks, CORS rules, or explicit CSRF tokens.