Information Disclosure in Chi with Basic Auth

Information Disclosure in Chi when Basic Auth is used centers on how credentials are transmitted, stored, and handled by the application. Chi is a compiled systems language that produces native binaries, and it does not inherently provide built-in protections for HTTP authentication mechanisms. When Basic Auth is implemented naively in a Chi application, the following risks can emerge.

Basic Auth sends credentials as a base64-encoded string in the Authorization header. Because base64 is easily reversible, any interceptor who captures the header can recover the credentials. In a Chi service, if TLS is not enforced on all routes, credentials can leak in cleartext across the network. A common pattern in Chi is to define routes with middleware that reads the header, but if that middleware is conditionally applied or omitted for certain paths, authentication can be bypassed entirely.

Another disclosure vector is server-side logging and error handling. In Chi, developers often write custom middleware for logging requests. If such middleware inadvertently logs the Authorization header, credentials can be persisted in log files, metrics systems, or error traces. Logs may be aggregated in external monitoring tools, unintentionally exposing secrets. Additionally, detailed error responses in Chi applications can reveal stack traces or configuration details that hint at how authentication is structured, aiding an attacker in crafting targeted information disclosure attempts.

Misconfigured CORS (Cross-Origin Resource Sharing) in a Chi service can also contribute to Information Disclosure. If CORS policies are too permissive, client-side JavaScript running in a browser can make authenticated requests and expose responses to origins that should not have access. Since Chi is commonly used to build APIs consumed by web frontends, improper CORS settings can lead to authenticated data being read by malicious sites.

Moreover, when Basic Auth credentials are cached or reused across requests without proper rotation, a compromised credential can lead to prolonged access. Chi applications that do not validate the scope and lifetime of credentials, or that accept credentials from query parameters or non-header locations, increase the surface for accidental exposure via referrer headers, browser history, or proxy logs.

Using middleBrick’s LLM/AI Security checks adds a layer of detection for prompt-injection attempts that could try to coax credentials or internal logic from AI-assisted development tools integrated into the Chi workflow. While middleBrick does not fix issues, its findings can highlight risky patterns such as hardcoded secrets in code snippets or insecure handling of tokens within AI-assisted code generation.

Remediation focuses on ensuring credentials are never exposed in clear text, logs, or error responses, and that authentication is consistently enforced across all routes.

• Always enforce HTTPS. Use Chi middleware to redirect HTTP to HTTPS and terminate TLS at the edge or load balancer. Never accept credentials over cleartext HTTP.
• Avoid logging sensitive headers. When adding logging middleware in Chi, explicitly exclude the Authorization header from logs.

import chi "github.com/go-chi/chi/v5"
import "net/http"

func main() {
    r := chi.NewRouter()

    // Middleware to strip sensitive headers from logs
    r.Use(func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            // Create a copy of the request without the Authorization header for logging
            // In practice, use a wrapper or a logging library that filters headers
            next.ServeHTTP(w, r)
        })
    })

    // Secure route requiring Basic Auth
    r.Get("/secure", func(w http.ResponseWriter, r *http.Request) {
        user, pass, ok := r.BasicAuth()
        if !ok || !validateCredentials(user, pass) {
            w.Header().Set("WWW-Authenticate", `Basic realm="restricted", charset="UTF-8"`)
            http.Error(w, "Unauthorized", http.StatusUnauthorized)
            return
        }
        w.Write([]byte("Authenticated"))
    })
}

func validateCredentials(user, pass string) bool {
    // Use constant-time comparison to avoid timing attacks
    expectedUser := "admin"
    expectedPass := "s3cr3t"
    return subtle.ConstantTimeCompare([]byte(user), []byte(expectedUser)) == 1 &&
           subtle.ConstantTimeCompare([]byte(pass), []byte(expectedPass)) == 1
}

• Do not pass credentials in query parameters or URL fragments. Always use the Authorization header.
• Implement short-lived credentials and rotate them regularly. Combine Basic Auth with other mechanisms where feasible, such as token-based authentication, to reduce reliance on static credentials.
• Use middleBrick’s GitHub Action to add API security checks to your CI/CD pipeline. Configure it to fail builds if risk scores drop below your threshold, ensuring that insecure authentication patterns are caught before deployment.