Clickjacking in Buffalo (Go)

Clickjacking is a client-side injection attack where an invisible or misleading UI layer tricks a user into interacting with a page they did not intend to interact with. When building web applications with the Buffalo framework in Go, the risk exists if the application does not enforce proper framing protections. Buffalo generates Go applications with sensible defaults, but it does not automatically add HTTP headers that prevent a site from being embedded in an iframe on another origin.

An attacker can host a malicious page that loads a vulnerable Buffalo application inside an invisible iframe and overlay interactive elements (buttons, links) on top of it. If the embedded application relies on the absence of an X-Frame-Options or Content-Security-Policy frame-ancestors directive, the user may inadvertently submit forms, change settings, or perform state-changing actions while believing they are interacting with the attacker’s page. This is especially relevant in Buffalo applications that render sensitive actions without verifying the request origin or enforcing strict CSP framing rules.

The attack leverages social engineering and browser behavior rather than a flaw in Go itself, but a Buffalo application written in Go must explicitly opt out of embedding. Without response headers that restrict framing (e.g., X-Frame-Options: DENY or a restrictive CSP frame-ancestors directive), the application remains susceptible. MiddleBrick’s security checks validate the presence and correctness of these headers as part of its unauthenticated scan, highlighting missing frame-protection controls in Buffalo-based APIs and web apps.

To remediate clickjacking in a Buffalo application written in Go, you should enforce strict framing rules via HTTP response headers. Buffalo provides middleware hooks where you can set these headers consistently across all responses.

1. Set X-Frame-Options globally in your application’s bootstrap file (typically app.go):

func app() *buffalo.App {
    if app == nil {
        app = buffalo.New(buffalo.Options{
            // ... other options
        })
        app.Use(func(next buffalo.Handler) buffalo.Handler {
            return buffalo.HandlerFunc(func(c buffalo.Context) error {
                c.Response().Header().Set("X-Frame-Options", "DENY")
                return next(c)
            })
        })
    }
    return app
}

2. Use a restrictive Content-Security-Policy header with frame-ancestors to allow embedding only from trusted sources (or none):

app.Use(func(next buffalo.Handler) buffalo.Handler {
    return buffalo.HandlerFunc(func(c buffalo.Context) error {
        c.Response().Header().Set("Content-Security-Policy", "frame-ancestors 'none'")
        return next(c)
    })
})

3. For cases where controlled embedding is required (e.g., internal dashboards), specify specific origins instead of 'none':

c.Response().Header().Set("Content-Security-Policy", "frame-ancestors 'self' https://trusted.example.com")

These middleware snippets integrate cleanly with Buffalo’s request lifecycle. By setting these headers in app.go, you ensure that all routes benefit from frame-protection. MiddleBrick’s scans can verify that these headers are present and correctly configured, reducing the attack surface for clickjacking against Buffalo services.