Arp Spoofing in Axum with Session Cookies

Arp Spoofing is a network-layer attack where an attacker sends falsified ARP messages to associate their MAC address with the IP address of another host, typically the gateway. In an Axum application that relies on Session Cookies for authentication, this attack does not directly compromise the cookie value, but it creates conditions that enable session hijacking. Because Axum often runs behind a router or switch in a local network, an attacker on the same network segment can intercept traffic between the client and server by poisoning ARP tables.

When an attacker successfully performs Arp Spoofing, they can observe or alter unencrypted HTTP traffic. If the application transmits Session Cookies over HTTP, the attacker can capture these cookies and reuse them to impersonate the victim. Even when cookies are transmitted over HTTPS, Arp Spoofing can facilitate SSL stripping or downgrade attacks if the server is misconfigured or if the client does not enforce strict HTTPS. Axum applications that set Session Cookies without the Secure and HttpOnly flags are especially vulnerable because cookies may be exposed to insecure channels or accessible via client-side scripts.

The combination of Arp Spoofing and Session Cookies becomes critical in environments where network segmentation is weak or where clients connect to untrusted networks, such as public Wi-Fi. The attack surface is not in Axum’s code but in the network path and cookie attributes. MiddleBrick scans can detect missing Secure and HttpOnly flags and flag them as findings under Data Exposure and Unsafe Consumption checks, highlighting risks that could be exploited in a spoofed network context.

Securing Session Cookies in Axum requires setting appropriate cookie attributes and ensuring all communication occurs over HTTPS. Below are concrete code examples that demonstrate how to configure cookies securely using the cookie` and `headers` crates commonly used in Axum applications.

use axum::{response::Response, http::HeaderMap, headers::HeaderValue};
use std::time::Duration;

fn build_secure_response() -> Response {
    let mut response = Response::new("OK".into());
    let cookie_value = "session_id=abc123; Path=/; Secure; HttpOnly; SameSite=Lax; Max-Age=3600";
    response.headers_mut().insert(
        axum::http::header::SET_COOKIE,
        HeaderValue::from_str(cookie_value).unwrap(),
    );
    response
}

This example sets a session cookie with Secure to ensure transmission only over HTTPS, HttpOnly to prevent JavaScript access, and SameSite=Lax to mitigate cross-site request forgery. The Max-Age attribute controls session lifetime, reducing the window for stolen cookie reuse.

use axum::{response::Response, http::HeaderMap, headers::HeaderValue};

fn update_cookie_with_rotation(response: &mut Response, old_session_id: &str) {
    let new_session_id = uuid::Uuid::new_v4().to_string();
    let cookie_value = format!(
        "session_id={}; Path=/; Secure; HttpOnly; SameSite=Strict; Max-Age=1800",
        new_session_id
    );
    response.headers_mut().insert(
        axum::http::header::SET_COOKIE,
        HeaderValue::from_str(&cookie_value).unwrap(),
    );
}

In this second example, session rotation is implemented after privilege changes or authentication events. Generating a new session ID and resetting the cookie minimizes the impact of a compromised cookie. MiddleBrick’s scans can verify that these attributes are present and flag endpoints that transmit cookies without Secure or HttpOnly.

Additionally, developers should enforce HTTPS at the infrastructure level using TLS termination and HSTS headers. MiddleBrick’s Encryption and Data Exposure checks validate that cookies are transmitted securely and that sensitive data is not exposed in logs or error messages.