Information Disclosure in Buffalo with Basic Auth

Buffalo is a popular Go web framework that encourages rapid development with sensible defaults. When Basic Authentication is used without additional protections, information disclosure can occur in ways that are specific to Buffalo’s request handling and response rendering pipeline.

Basic Auth sends credentials in an Authorization header as base64(username:password). While base64 is not encryption, it is easily reversible. If a Buffalo application uses Basic Auth for access control but does not enforce HTTPS, credentials can be intercepted in transit. Even when HTTPS is used, misconfiguration can expose sensitive details through error messages, logs, or debug pages that Buffalo generates during request processing.

Buffalo’s HTML rendering stack can inadvertently disclose information when templates do not properly sanitize user input or when developers embed request or environment details into error pages. For example, a Buffalo app that uses the buffalo-pop ORM and exposes stack traces in development mode might include database connection strings or model field names in error responses. An attacker who triggers an error condition (e.g., by sending malformed requests or missing authentication) can learn about internal data structures, endpoint behavior, or configuration details that should remain private.

The interaction between authentication and authorization also plays a role. Basic Auth typically provides authentication (who you are) but not granular authorization (what you are allowed to do). If authorization checks are inconsistent or omitted, an authenticated user might access endpoints or data they should not, leading to information disclosure. Buffalo applications that rely solely on route-level Basic Auth guards without per-action or per-resource checks can expose sensitive data through IDOR-like patterns or predictable resource identifiers.

Buffalo’s middleware pipeline processes requests in a defined order. If security middleware is placed after rendering or logging middleware, sensitive information may be logged or included in responses before authentication is fully validated. This ordering issue can result in credentials or session-like data being written to logs or exposed through verbose error pages, especially when debugging is enabled in production.

To detect this class of issue with middleBrick, an unauthenticated scan runs checks across the 12 security categories, including Authentication, Data Exposure, and Input Validation. The scanner looks for missing HTTPS, verbose error messages, and endpoints that return sensitive data without proper authorization. Findings include severity ratings and remediation guidance mapped to frameworks like OWASP API Top 10 and compliance standards such as PCI-DSS and SOC2.

Remediation focuses on ensuring that Basic Auth is used only over HTTPS, that errors do not leak internal details, and that authorization is consistently enforced. Below are concrete examples showing how to implement secure Basic Auth in a Buffalo application.

Enforce HTTPS and secure transport

Always enforce HTTPS to protect credentials in transit. Use middleware to redirect HTTP requests to HTTPS and ensure the Authorization header is never sent over cleartext connections.

// app/middleware/secure_redirect.go
package middleware

import (
    "net/http"
)

// SecureRedirect ensures all requests use HTTPS in production.
func SecureRedirect(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        if r.Header.Get("X-Forwarded-Proto") == "http" {
            http.Redirect(w, r, "https://"+r.Host+r.RequestURI, http.StatusPermanentRedirect)
            return
        }
        next.ServeHTTP(w, r)
    })
}

Use authenticated actions with proper error handling

Buffalo uses actions to handle requests. Wrap authentication logic in a before action and ensure errors do not expose stack traces or internal paths in production.

// app/actions/app.go
package actions

import (
    "net/http"
    "github.com/gobuffalo/buffalo"
)

// AuthRequired is a before action that checks Basic Auth credentials.
func AuthRequired(next buffalo.HandlerFunc) buffalo.HandlerFunc {
    return func(c buffalo.Context) error {
        user, pass, ok := c.Request().BasicAuth()
        if !ok || !validateCredentials(user, pass) {
            c.Response().Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
            return c.Render(http.StatusUnauthorized, r.JSON(map[string]string{"error": "unauthorized"}))
        }
        return next(c)
    }
}

func validateCredentials(user, pass string) bool {
    // Use constant-time comparison in production.
    return user == "admin" && pass == "s3cr3t"
}

Disable detailed errors in production

Ensure that Buffalo’s development error reporting is disabled in production to prevent information disclosure through verbose messages.

// config/env/production.go
package env

import (
    "github.com/gobuffalo/packr/v2"
    "github.com/gobuffalo/packr/v2/packr2"
    "github.com/gobuffalo/buffalo"
)

func Production() *buffalo.App {
    app := buffalo.New(buffalo.Options{
        Env:         ENV,
        SessionStore: cache.New(),
        PreWares:    []buffalo.PreWare{AuthRequired},
        // Disable detailed error pages in production.
        DisableErrorDetail: true,
    })
    return app
}

Avoid logging sensitive information

Configure logging middleware to redact or omit the Authorization header from logs. Buffalo allows customization of log formats to prevent credential exposure in log files.

// app/middleware/logging.go
package middleware

import (
    "net/http"
    "strings"
)

// SanitizeLogging removes sensitive headers from request logs.
func SanitizeLogging(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        // Strip Authorization header from copies used for logging.
        safeHeader := http.Header{}
        for k, v := range r.Header {
            if strings.ToLower(k) != "authorization" {
                safeHeader[k] = v
            }
        }
        r.Header = safeHeader
        next.SafeServeHTTP(w, r)
    })
}

Combine with per-action authorization checks

Even when using Basic Auth, enforce authorization at the action or resource level to prevent IDOR-style access to data.

// app/actions/users.go
package actions

import (
    "net/http"
    "github.com/gobuffalo/buffalo"
)

func ShowUser(c buffalo.Context) error {
    requestedID := c.Param("user_id")
    currentUser := c.Value("current_user").(string) // set by AuthRequired
    if currentUser != requestedID {
        return c.Render(http.StatusForbidden, r.JSON(map[string]string{"error": "forbidden"}))
    }
    // Fetch and return user data safely.
    return c.Render(http.StatusOK, r.JSON(fetchUserData(requestedID)))
}

These steps reduce information disclosure by ensuring credentials are protected in transit, errors are safe, and authorization is consistently applied. Using middleBrick’s scans, you can verify that HTTPS is enforced, error messages do not expose details, and endpoints requiring authentication are properly guarded.