Dictionary Attack in Buffalo

In a Buffalo application, a dictionary attack typically targets endpoints that accept credentials, such as a login handler built with buffalo.Context. The attacker sends many requests, each containing a username and a password guessed from a common‑password list, hoping to find a match. Because the handler often checks the password with a simple string comparison or a fast hash, and there is no throttling, the server processes each guess as fast as the network allows.

package actions

import (
	"github.com/gobuffalo/buffalo"
	"github.com/gobuffalo/pop/v5"
	"myapp/models"
)

func Login(c buffalo.Context) error {
	u := &models.User{}
	// Bind form data (username, password) into a temporary struct
	if err := c.Bind(u); err != nil {
		return err
	}

	// Lookup user by username
	tx := c.Value("tx").(*pop.Connection)
	err := tx.Where("email = ?", u.Email).First(u)
	if err != nil {
		// User not found – still return generic error to avoid user enumeration
		return c.Render(401, r.HTML("login.html"))
	}

	// Insecure: direct string comparison (no hashing)
	if u.Password != c.Request().FormValue("password") {
		return c.Render(401, r.HTML("login.html"))
	}

	// Successful login – set session
	session := c.Session()
	session.Set("current_user_id", u.ID)
	return c.Redirect(302, "/")
}

The code above shows two weaknesses that enable a dictionary attack:

Passwords are stored and compared in plain text (or with a fast, unsalted hash).
There is no limit on how many login attempts can be made from a single IP or session, allowing an attacker to send thousands of guesses per minute.

Even if the password were hashed with bcrypt, the absence of request‑rate limiting would still allow rapid offline‑style guessing, because each guess triggers a hash computation that the attacker can parallelize.

middleBrick performs unauthenticated black‑box scanning of any API endpoint, including those built with Buffalo. When it encounters a login‑like endpoint (e.g., POST /login), it automatically runs the following checks that reveal a dictionary‑attack risk:

• Rate Limiting – middleBrick sends a burst of requests (default 20 in 10 seconds) and measures whether the response code or headers change to indicate throttling. If the endpoint returns the same success/failure status for every request, the check flags missing rate limiting.
• Input Validation – the scanner probes for common password‑list entries (e.g., 123456, password) and looks for patterns in the response that suggest a successful login (session cookie, redirect, JWT). A high success rate on guessed credentials indicates weak password storage.
• Authentication – middleBrick verifies whether the endpoint leaks user‑existence information (different error messages for unknown vs. wrong password) which can aid an attacker in enumerating valid accounts.

To scan a Buffalo service with the CLI, run:

middlebrick scan https://api.example.com/login

The output includes a risk score (A–F), a breakdown per category, and prioritized findings with severity and remediation guidance. For example, a finding might read:

Missing Rate Limiting on POST /login – Severity: High – Remediation: Implement request‑throttling middleware to limit login attempts per IP or session.

Because middleBrick requires no agents, no configuration, and no credentials, you can point it at a staging or production Buffalo API and receive actionable results in 5–15 seconds.

Fixing a dictionary‑attack vulnerability in Buffalo involves adding proper password hashing, request‑rate limiting, and secure session handling using the framework’s built‑in libraries.

First, store passwords with a strong, slow hash such as bcrypt. Buffalo does not bundle a hashing package, but the standard golang.org/x/crypto/bcrypt works seamlessly:

package models

import (
	"golang.org/x/crypto/bcrypt"
)

func (u *User) SetPassword(raw string) error {
	hash, err := bcrypt.GenerateFromPassword([]byte(raw), bcrypt.DefaultCost)
	if err != nil {
		return err
	}

u.PasswordHash = string(hash)
	return nil
}

func (u *User) CheckPassword(raw string) bool {
	err := bcrypt.CompareHashAndPassword([]byte(u.PasswordHash), []byte(raw))
	return err == nil
}

Next, protect the login endpoint with rate limiting. Buffalo’s middleware system lets you attach a handler that counts attempts per IP (or per session) and returns 429 Too Many Requests when a threshold is exceeded. The following example uses a simple in‑memory counter; for production you would replace it with a distributed store such as Redis:
package middleware

import (
	"github.com/gobuffalo/buffalo"
	"sync"
	"time"
)

type ipCounter struct {
	count int
	first time.Time
	mu    sync.Mutex
}

var counters = struct {
	sync.Map
}{}

func RateLimiter(next buffalo.Handler) buffalo.Handler {
	return func(c buffalo.Context) error {
	ip := c.Request().RemoteAddr
	val, _ := counters.Map.LoadOrStore(ip, &ipCounter{})
	cnt := val.(*ipCounter)

	cnt.mu.Lock()
	defer cnt.mu.Unlock()

	now := time.Now()
	if now.Sub(cnt.first) > 1*time.Minute {
		// reset window
		cnt.count = 0
		cnt.first = now
	}
	cnt.count++
	if cnt.count > 10 { // allow 10 attempts per minute
		return c.Error(429, nil)
	}
	return next(c)
	}
}

Apply the middleware to the login route in actions/app.go:
func App() *buffalo.App {
	app := buffalo.New(buffalo.Options{})
	app.POST("/login", Auth.Login).Use(middleware.RateLimiter)
	return app
}

Finally, ensure the login handler uses the secure password check and sets HTTP‑only, SameSite session cookies:
func Login(c buffalo.Context) error {
	u := &models.User{}
	if err := c.Bind(u); err != nil {
		return err
	}

	tx := c.Value("tx").(*pop.Connection)
	dbUser := &models.User{}
	err := tx.Where("email = ?", u.Email).First(dbUser)
	if err != nil {
		// generic failure to avoid user enumeration
		return c.Render(401, r.HTML("login.html"))
	}

	if !dbUser.CheckPassword(u.Password) {
		return c.Render(401, r.HTML("login.html"))
	}

	session := c.Session()
	session.Set("current_user_id", dbUser.ID)
	session.Options().HTTPOnly = true
	session.Options().SameSite = http.SameSiteStrictMode
	return c.Redirect(302, "/")
}

With these changes, the endpoint now:

Stores passwords using bcrypt, making each guess computationally expensive.
Limits login attempts to 10 per minute per IP, throttling automated guessing.
Returns identical error messages for unknown users and incorrect passwords, preventing account enumeration.
Sets secure session attributes, reducing the risk of session hijacking after a successful login.

Re‑scan the API with middleBrick to verify that the risk score improves (e.g., from F to B) and that the findings no longer include missing rate limiting or plain‑text password comparison.