Man In The Middle in Buffalo

In Buffalo web applications, Man-in-the-Middle (MitM) attacks commonly target unencrypted HTTP traffic between clients and the server, particularly when serving static assets or handling API requests over public networks. A specific vulnerability arises when developers configure buffalo.New() without enforcing HTTPS, allowing attackers on the same network (e.g., public Wi-Fi) to intercept, modify, or inject malicious content into responses. For example, if a Buffalo app serves a JavaScript file via assets.FileServer() over HTTP, an attacker could alter the script to exfiltrate form data or redirect users to phishing sites. Another vector occurs when WebSocket endpoints (handled via github.com/gorilla/websocket in Buffalo) are upgraded without TLS, enabling session hijacking through stolen ws:// connections. Real-world parallels include CVE-2021-42792 in Apache HTTP Server, where misconfigured proxies allowed request smuggling to facilitate MitM, though in Buffalo the root cause is typically missing TLS enforcement at the framework level rather than proxy misconfiguration.

Detecting MitM risks in Buffalo applications begins with identifying endpoints served over HTTP instead of HTTPS. middleBrick scans for this by making unauthenticated requests to the target URL and analyzing response headers for missing security indicators like Strict-Transport-Security (HSTS) and checking whether the endpoint upgrades HTTP to HTTPS. For instance, if a request to http://api.example.com/users returns a 200 without redirecting to HTTPS, middleBrick flags this as a potential MitM exposure. Additionally, the scanner checks for mixed content: if an HTTPS page loads scripts or API calls via HTTP (e.g., <script src='http://assets.example.com/app.js'>), it triggers a finding under Data Exposure. middleBrick also tests for SSL/TLS misconfigurations such as weak cipher suites or expired certificates by performing a handshake analysis during the scan. These checks are part of the Encryption and Data Exposure categories, providing severity ratings and remediation guidance directly in the report.

To mitigate MitM risks in Buffalo applications, enforce HTTPS at the framework level. Use buffalo.New() with TLS configuration or deploy behind a reverse proxy that redirects HTTP to HTTPS. In code, apply middleware to redirect all HTTP requests:

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

func secureMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		if r.Header.Get("X-Forwarded-Proto") != "https" {
			http.Redirect(rw, r, "https://"+r.Host+r.RequestURI, http.StatusMovedPermanently)
			return
		}
		next.ServeHTTP(rw, r)
	})
}

func main() {
	app := buffalo.New(buffalo.Options{})
	app.Use(secureMiddleware)
	app.GET("/api/data", handlers.ListData)
	app.Serve()
}
This middleware checks the X-Forwarded-Proto header (set by proxies like NGINX or AWS ALB) and redirects non-HTTPS requests. For direct TLS termination in Buffalo, configure app.ServeTLS: 
app.ServeTLS("localhost:3000", "cert.pem", "key.pem")
Additionally, set HSTS headers to prevent protocol downgrade: 
app.Use(func(next http.Handler) http.Handler {
	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
		rw.Header().Set("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
		next.ServeHTTP(rw, r)
	})
})
These fixes ensure all communication is encrypted, eliminating the attack surface for passive eavesdropping and active tampering. middleBrick validates these mitigations by rescanning the endpoint and confirming HTTPS enforcement and secure headers.