Arp Spoofing in Axum with Mssql

Arp spoofing is a Layer 2 network attack where an attacker sends falsified Address Resolution Protocol messages to associate their MAC address with the IP address of a legitimate host, such as a database server. In an Axum application that connects to Microsoft SQL Server (Mssql), this can expose credentials, query contents, and result sets if the traffic is intercepted and modified.

When Axum services communicate with Mssql over the network—whether via connection strings that point to a remote host or through linked-server scenarios—ARP resolution is used to map the Mssql server’s IP to its MAC address. If an attacker on the same broadcast segment spoofs the Mssql server’s IP, the Axum application may unknowingly send sensitive TDS (Tabular Data Stream) traffic to the attacker, enabling passive sniffing or active manipulation. This risk is elevated in environments that do not enforce strict network segmentation between application tiers and database hosts.

Because Axum applications often rely on connection pooling and asynchronous I/O to interact with Mssql, intercepted or altered ARP responses can redirect traffic without breaking the application-level protocol logic, making the intrusion harder to detect. Attackers may leverage this to perform credential theft via packet capture or inject malicious TDS packets to escalate privileges or extract data. MiddleBrick scans help detect unauthenticated exposure and network-level attack surfaces, highlighting risks when Axum endpoints interact with Mssql in shared or poorly segmented networks.

Remediation focuses on minimizing exposure over Layer 2 networks and hardening how Axum communicates with Mssql. Use encrypted connections, restrict network paths, and avoid embedding sensitive data in logs or error messages.

1. Enforce encrypted connections to Mssql

Ensure your Axum application connects to Mssql using encrypted channels (TLS). Update the connection string to require encryption and validate server certificates.

use axum::{
    routing::get,
    Router,
};
use sqlx::mssql::MssqlConnectOptions;
use sqlx::ConnectOptions;
use std::net::SocketAddr;

#[tokio::main]
async fn main() {
    // Enforce encrypted connection to Mssql with certificate validation
    let mut opts = MssqlConnectOptions::new("sqlserver://user:password@mssql.example.com:1433");
    opts.encrypt(sqlx::mssql::MssqlEncrypt::Required)
        .trust_cert(false); // Use full CA chain in production

    let pool = sqlx::mssql::MssqlPool::connect_with(opts)
        .await
        .expect("Failed to connect to Mssql");

    let app = Router::new().route("/health", get(|| async { "ok" }));
    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}

2. Use Windows Authentication or integrated security where possible

Prefer integrated security mechanisms to avoid sending plaintext credentials over the wire. When using SQL authentication, ensure secrets are managed via secure vaults and never logged.

use sqlx::mssql::MssqlConnectOptions;

let mut opts = MssqlConnectOptions::new("sqlserver://mssql.example.com:1433");
// If using SQL auth, avoid embedding credentials in code; use environment variables
let username = std::env::var("MSSQL_USER").expect("MSSQL_USER not set");
let password = std::env::var("MSSQL_PASSWORD").expect("MSSQL_PASSWORD not set");
opts = opts.username(&username).password(&password)
    .encrypt(sqlx::mssql::MssqlEncrypt::Required);

let pool = sqlx::mssql::MssqlPool::connect_with(opts).await.unwrap();

3. Restrict network exposure and monitor ARP behavior

Place Axum and Mssql in separate network zones, use firewalls to limit direct access, and monitor for unusual ARP replies. While Axum does not manage network layers, infrastructure controls reduce the attack surface that enables ARP spoofing.

-- Example Mssql firewall rule via endpoint (illustrative):
-- Only allow Axum server IPs to reach Mssql port
-- This is enforced outside the application, e.g., in cloud security groups or on-premise firewall ACLs.

4. Avoid logging sensitive query details that could aid attackers

Ensure Axum middleware does not inadvertently log full queries or parameters that could be reconstructed from intercepted traffic.

use axum::middleware::Next;
use axum::extract::Request;

async fn no_sensitive_logging_middleware(req: Request, next: Next) -> axum::response::Response {
    // Sanitize or omit sensitive headers/params before logging
    let method = req.method().clone();
    let uri = req.uri().path().to_string(); // Do not log full URI with credentials
    tracing::info!("request method={} path={}", method, uri);
    next.run(req).await
}