Arp Spoofing in Axum with Cockroachdb

Arp spoofing is a Layer 2 attack where an adversary sends falsified ARP messages to associate their MAC address with the IP address of a legitimate host, typically the database server. In an Axum service that communicates with CockroachDB, this can redirect database traffic to the attacker, enabling interception, modification, or denial of database responses. The exposure arises because Axum applications often run as networked services in the same broadcast domain as the database or through container networks where ARP visibility is higher.

When Axum routes connect to a CockroachDB node using a service IP or hostname that resolves to a virtual IP (e.g., a load balancer or a Kubernetes service), ARP responses can overwrite the correct MAC mapping for that IP. If traffic is not encrypted in transit, or if encryption is terminated on a sidecar or proxy with a misconfigured certificate, an attacker positioned on the same network can intercept SQL queries and results. CockroachDB’s wire protocol does not inherently prevent ARP spoofing; it relies on the underlying network stack and transport security. Therefore, an Axum application using synchronous or streaming SQL clients can unknowingly send credentials, queries, and result sets to an attacker-controlled host.

Specific risk patterns include:

• Unencrypted database connections (plaintext TCP) within a shared VPC or pod network where ARP is observable and mutable.
• Long-lived database sessions from Axum connection pools that do not re-verify server identity after ARP changes.
• Service discovery mechanisms that cache IP-to-MAC mappings without revalidation, allowing stale or malicious entries to persist across deployments.

Although CockroachDB supports TLS for client connections, ARP spoofing remains viable if the attacker can also manipulate DNS or IP routing to maintain reachability, or if TLS verification is not strictly enforced in the Axum client configuration.

Remediation centers on enforcing strict transport security and reducing reliance on mutable Layer 2 mappings. In Axum, ensure database clients validate server certificates and pin identities where possible. Use synchronous TLS connections for every database interaction and avoid long-lived unencrypted sessions.

Example Axum route connecting securely to CockroachDB with Rust TLS configuration:

use axum::{routing::get, Router};
use cockroach_client::SecureConnectOptions;
use std::net::SocketAddr;
use tokio::net::TcpStream;
use tokio_rustls::rustls::{ClientConfig, RootCertStore};
use tokio_rustls::TlsConnector;

async fn secure_db_pool() -> Result<(), Box> {
    let mut root_store = RootCertStore::empty();
    // Load your organization’s CA bundle or CockroachDB cert
    root_store.add(&rustls_pemfile::certs(&mut std::io::BufReader::new(
        std::fs::File::open("certs/ca.pem")?,
    ))?[0])
    .expect("valid cert");

    let config = ClientConfig::builder()
        .with_safe_defaults()
        .with_root_certificates(root_store)
        .with_no_client_auth();

    let connector = TlsConnector::from(std::sync::Arc::new(config));
    let tcp = TcpStream::connect("cockroachdb-public:26257").await?;
    let tls_conn = connector.connect("cockroachdb-public".try_into()?, tcp).await?;

    // Use cockroach_client or a compatible driver that accepts a TLS stream
    let client = cockroach_client::Client::new(tls_conn, SecureConnectOptions::default())
        .require_ssl_mode("verify-full")
        .ssl_root_cert("certs/ca.pem")
        .build()
        .await?;

    let rows = client
        .query("SELECT username, email FROM users WHERE id = $1", &[&1i32])
        .await?;

    for row in rows {
        let username: String = row.get(0);
        println!("User: {}", username);
    }
    Ok(())
}

Key practices:

• Enforce certificate verification with require_ssl_mode set to verify-full so that the Axum client validates the CockroachDB server certificate chain and hostname.
• Pin the server certificate or public key in environments where PKI changes are controlled, reducing reliance on CA updates that may be delayed.
• Use mTLS if CockroachDB cluster nodes require client certificates, ensuring that both endpoints authenticate each other via Axum’s TLS layer.
• Rotate credentials and certificates regularly, and employ short-lived tokens for database access where supported.
• Segment networks so that Axum application pods and CockroachDB nodes reside in isolated subnets or security groups, reducing ARP visibility across unrelated workloads.