Arp Spoofing in Buffalo with Cockroachdb

Arp spoofing targets the Address Resolution Protocol, which maps IP addresses to MAC addresses on a local network. In a Buffalo deployment that uses Cockroachdb for distributed SQL data storage, this attack can undermine the confidentiality and integrity of database traffic. When an attacker spoofs ARP replies on the Buffalo network segment, hosts may send database-bound packets to the attacker’s machine instead of the intended Cockroachdb node. Because Cockroachdb often communicates over plaintext HTTP/2 or TLS without mandatory certificate pinning in certain client configurations, intercepted traffic may expose authentication credentials, query patterns, or result sets.

The combination of Buffalo and Cockroachdb can increase exposure when services are deployed in a flat network without host-level isolation or network segmentation. Buffalo applications that open database connections using a service principal or long-lived session may unknowingly route those connections through a compromised host during an ARP spoofing event. An attacker who successfully positions themselves between a Buffalo web process and a Cockroachdb node can observe unencrypted metadata or, if TLS is misconfigured, conduct man-in-the-middle activities such as session hijacking or credential replay. This matters because Buffalo routes and request contexts may carry sensitive identifiers that, when correlated with Cockroachdb audit logs, enable deeper lateral movement within the cluster.

Importantly, middleBrick does not test for ARP spoofing as part of its unauthenticated black-box checks, since ARP operates below the application layer and requires network-level access. However, findings from related security checks—such as missing encryption, weak transport-layer configurations, or lack of input validation on database-bound requests—can indicate whether a Buffalo+Cockroachdb deployment is at risk if an attacker gains a position to perform ARP spoofing. For example, if the scanner detects that Cockroachdb endpoints accept unencrypted HTTP on non-loopback interfaces, the implied transport risk is heightened in a local network where ARP spoofing is feasible.

To reduce the impact of ARP spoofing risks in a Buffalo application using Cockroachdb, focus on transport hardening, strict network policies, and secure connection handling. The following practices and code examples assume a typical Elixir Buffalo project with an HTTP API layer and a Cockroachdb cluster reachable via a connection pool.

1. Enforce TLS for all Cockroachdb connections

Ensure that every Cockroachdb client connection uses TLS with verified server certificates. In Buffalo, configure the database repository to use SSL modes that reject unencrypted or improperly validated connections.

config :my_app, MyApp.Repo,
  url: "postgresql://myuser:mypassword@cockroachdb-node:26257/mydb?sslmode=verify-full",
  ssl: true,
  ssl_opts: [
    certfile: "/path/to/client-cert.pem",
    keyfile: "/path/to/client-key.pem",
    cacertfile: "/path/to/ca.pem"
  ]

Using sslmode=verify-full ensures the server certificate matches the expected hostname, mitigating interception via ARP spoofing. Place certificate files in a non-world-readable directory and avoid embedding secrets in source code.

2. Restrict network interfaces and use firewall rules

Limit which interfaces Buffalo and Cockroachdb listen on. Bind services to localhost or specific VPC interfaces and use firewall rules to prevent external hosts from initiating connections that could be spoofed.

# In config/prod.exs for Buffalo
config :my_app, MyAppWeb.Endpoint,
  http: [ip: {127, 0, 0, 1}, port: 4000],
  debug_errors: false,
  code_reloader: false

For Cockroachdb, start nodes with --advertise-addr and --listen-addr restricted to private IPs. Combine this with host-based firewall rules (e.g., nftables or cloud security groups) so only trusted application hosts can reach the database port.

3. Use secure authentication and short-lived credentials

Avoid long-lived database credentials that are attractive targets in a spoofed environment. Use role-based credentials issued by an authentication proxy or Vault, and ensure Buffalo connects using per-request or short-lived tokens where possible.

# Example of dynamic credential acquisition (pseudo-code)
defmodule MyApp.CockroachConnector do
  def get_creds do
    # Retrieve a temporary certificate or password from Vault
    Vault.credentials("cockroachdb/app")
  end

  def repo_opts do
    creds = get_creds()
    [
      url: "postgresql://#{creds.user}:#{creds.password}@cockroachdb-node:26257/mydb?sslmode=verify-full",
      ssl: true,
      ssl_opts: [
        certfile: creds.cert_path,
        keyfile: creds.key_path,
        cacertfile: creds.ca_path
      ]
    ]
  end
end

Rotate credentials frequently and revoke compromised certificates immediately. This reduces the window of usefulness for any credentials that might be intercepted via ARP spoofing.

4. Employ host-level network security

Enable secure neighbor discovery (e.g., arpwatch or switch port security) and consider using IPsec or mutual TLS at the transport layer to add protections that operate below the application layer. While Buffalo itself does not manage these OS-level settings, ensuring they are part of your deployment runbooks complements the application-layer mitigations.