Arp Spoofing in Fiber with Cockroachdb

Arp spoofing is a Layer 2 attack where an attacker sends falsified ARP messages to associate their MAC address with the IP of a legitimate host, typically the database server. In a setup using the Fiber web framework with CockroachDB as the backend database, this attack targets the database connection path between the application and the cluster nodes. Even though Fiber handles HTTP routing and middleware, the vulnerability is introduced by how database connections are established and trusted on the network.

When Fiber applications connect to CockroachDB using standard TCP connection strings (e.g., hostnames or private IPs), the client relies on ARP resolution to reach the database node. If an attacker performs ARP spoofing on the same network segment (or a compromised host on the path), they can intercept or modify database traffic intended for CockroachDB. This becomes particularly risky in environments without TLS encryption or when TLS is misconfigured, as the attacker may observe or alter SQL queries and results. Because CockroachDB often runs as a distributed cluster with nodes communicating continuously, spoofed ARP replies can redirect connections, enabling man-in-the-middle (MITM) behavior between the Fiber app and the database.

Although middleBrick focuses on detection and reporting rather than network-layer exploitation, scanning a Fiber endpoint that connects to CockroachDB can uncover risk indicators related to weak transport security and missing host integrity checks. For example, if the scan detects that database connections do not enforce strict certificate validation or rely on unencrypted HTTP alongside CockroachDB’s insecure flags, it may highlight findings tied to data exposure and insecure consumption. These findings map to the OWASP API Top 10 and reflect real-world attack patterns such as MITM and credential theft via compromised network paths.

Importantly, the vulnerability is not caused by Fiber or CockroachDB themselves, but by deployment configurations that do not account for ARP spoofing risks. This includes running CockroachDB without TLS, using predictable internal IPs without additional network segmentation, or allowing unrestricted access at the network layer. The scan findings emphasize the need for strict transport security and validation of server identity, rather than implying that the tools themselves are insecure.

To mitigate ARP spoofing risks when Fiber connects to CockroachDB, enforce strong transport security and identity verification. The primary defense is to use encrypted connections with strict certificate validation and avoid relying on network-level trust. Below are concrete code examples demonstrating secure configurations.

First, ensure your CockroachDB cluster is configured with TLS certificates. Each node should have a CA certificate, node certificate, and node key. Then configure the Fiber application to use these certificates when establishing database connections. In Go, you can set up a secure *sql.DB instance using sql.Open with a properly configured connection string and TLS settings.

// main.go
package main

import (
    "database/sql"
    "fmt"
    "log"
    "net/http"
    "os"

    "github.com/gofiber/fiber/v2"
    _ "github.com/lib/pq"
)

func main() {
    // Load certificates
    sslCert := "path/to/client.crt"
    sslKey := "path/to/client.key"
    sslRootCert := "path_to_ca.crt"

    // Build connection string with SSL mode require and root certificate
    connStr := fmt.Sprintf(
        "host=%s port=%s user=%s password=%s dbname=%s sslmode=verify-full sslcert=%s sslkey=%s sslrootcert=%s",
        os.Getenv("DB_HOST"),
        os.Getenv("DB_PORT"),
        os.Getenv("DB_USER"),
        os.Getenv("DB_PASSWORD"),
        os.Getenv("DB_NAME"),
        sslCert,
        sslKey,
        sslRootCert,
    )

    db, err := sql.Open("postgres", connStr)
    if err != nil {
        log.Fatalf("failed to connect to database: %v", err)
    }
    defer db.Close()

    // Verify the connection
    if err := db.Ping(); err != nil {
        log.Fatalf("database ping failed: %v", err)
    }

    app := fiber.New()

    app.Get("/health", func(c *fiber.Ctx) error {
        var version string
        if err := db.QueryRow("SELECT version()").Scan(&version); err != nil {
            return c.Status(http.StatusInternalServerError).JSON(fiber.Map{"error": "database error"})
        }
        return c.JSON(fiber.Map{"version": version, "status": "ok"})
    })

    log.Fatal(app.Listen(":3000"))
}

In this example, sslmode=verify-full ensures that the client verifies the CockroachDB server certificate against the provided CA, preventing spoofing by invalid certificates. The client certificate and key enable mutual TLS, adding another layer of authentication. Additionally, avoid using hostnames that can be easily spoofed; prefer stable internal DNS names or IPs that are protected by network policies.

For environments where network segmentation is not feasible, consider placing the database behind a service mesh or VPN to reduce exposure to ARP spoofing. Regularly rotate certificates and monitor connection logs for anomalies. These practices complement scanning tools like middleBrick, which can identify missing encryption or weak configuration in your API endpoints and integrations.