Broken Authentication in Axum with Cockroachdb

Broken Authentication in an Axum service backed by Cockroachdb often stems from mismatched trust boundaries and session handling. Axum is a Rust web framework that is async-first and relies heavily on typed extractors and middleware to manage requests. When authentication logic is implemented as extractors or handlers without rigorous validation of credentials, tokens, and session state, the risk of Broken Authentication increases.

In this stack, Cockroachdb is typically used as the distributed SQL database storing user records, password hashes, and session tokens. If Axum routes query construction or parameter binding insecurely — for example, by concatenating user input into SQL strings or failing to enforce prepared statements — attackers can manipulate authentication flows via SQL injection or IDOR. Cockroachdb’s PostgreSQL compatibility means parameterized queries are essential; raw string concatenation bypasses type safety and enables authentication bypass.

A common pattern is an Axum login handler that deserializes JSON into a struct, then executes a Cockroachdb query to fetch a user. If the handler does not enforce constant-time password verification, or if session tokens are stored in plaintext cookies without the Secure and HttpOnly flags, the authentication surface is widened. Additionally, missing or weak rate limiting on authentication endpoints enables credential stuffing, which can be executed against the Cockroachdb-backed user store.

OpenAPI/Swagger spec analysis can surface these risks by correlating authentication requirements defined in the spec with runtime behavior. For instance, if an endpoint is marked as requiring an API key or OAuth2 scope but the Axum implementation lacks an extractor to validate the token against Cockroachdb, the scan reports a Broken Authentication finding. MiddleBrick’s checks include Authentication, BOLA/IDOR, and Unsafe Consumption, which map to this scenario by detecting unauthenticated access paths and insecure handling of credentials.

Real-world attack patterns include session fixation, where an attacker sets a user’s session identifier and waits for authentication, or token tampering, where a JWT with a weak algorithm (e.g., none) is accepted by Axum middleware. Because Cockroachdb stores the source of truth for identities, any leakage or misconfiguration in how Axum reads and writes authentication data directly impacts integrity.

Remediation centers on strict parameter handling, secure credential storage, and explicit authentication checks before database access. In Axum, prefer typed extractors and middleware to enforce authentication rather than scattering checks across handlers. Use Cockroachdb’s PostgreSQL wire protocol with a driver that supports prepared statements to prevent injection.

Example: a secure login handler using Axum extractors and the postgres crate with Cockroachdb.

use axum::{
    extract::State,
    http::StatusCode,
    response::IntoResponse,
    routing::post,
    Router,
};
use serde::{Deserialize, Serialize};
use std::net::SocketAddr;
use postgres::{NoTls, Client};
use bcrypt::{hash, verify, DEFAULT_COST};

#[derive(Deserialize)]
struct LoginRequest {
    username: String,
    password: String,
}

#[derive(Serialize)]
struct LoginResponse {
    token: String,
}

struct AppState {
    db_client: Client,
}

async fn login(
    State(state): State<AppState>,
    body: axum::Json<LoginRequest>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let user = state.db_client
        .query_one(
            "SELECT id, password_hash FROM users WHERE username = $1",
            &[&body.username],
        )
        .map_err(|_| (StatusCode::UNAUTHORIZED, "Invalid credentials".to_string()))?;

    let stored_hash: &str = user.get(1);
    let valid = verify(&body.password, stored_hash)
        .map_err(|_| (StatusCode::INTERNAL_SERVER_ERROR, "Verification error".to_string()))?;

    if !valid {
        return Err((StatusCode::UNAUTHORIZED, "Invalid credentials".to_string()));
    }

    let token = uuid::Uuid::new_v4().to_string();
    // Store token securely in Cockroachdb with an expiration
    state.db_client.execute(
        "INSERT INTO sessions (user_id, token, expires_at) VALUES ($1, $2, now() + interval '1 hour')",
        &[&user.get<i64>(0), &token],
    ).map_err(|_| (StatusCode::INTERNAL_SERVER_ERROR, "Session creation failed".to_string()))?;

    Ok((StatusCode::OK, axum::Json(LoginResponse { token })).into_response())
}

#[tokio::main]
async fn main() {
    let mut client = Client::connect("host=localhost user=app password=secret dbname=mydb sslmode=require", NoTls)
        .expect("Failed to connect to Cockroachdb");
    // Ensure prepared statements are used; avoid string concatenation
    let app = Router::new()
        .route("/login", post(login))
        .with_state(AppState { db_client: client });

    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}

Key practices:

• Always use parameterized queries ($1, $2) with the Cockroachdb driver; never interpolate user input into SQL strings.
• Store passwords using adaptive hashing (e.g., bcrypt) and verify with constant-time checks.
• Issue short-lived tokens and store them in Cockroachdb with expiration; set Secure, HttpOnly, and SameSite attributes on cookies if used.
• Apply rate limiting at the Axum middleware layer to protect authentication endpoints from brute force and credential stuffing.
• Validate and enforce authentication via Axum extractors (e.g., a custom AuthUser extractor) before allowing access to protected routes, ensuring each request is verified against Cockroachdb.

These steps align with OWASP API Top 10 2023:2023 Broken Authentication and can be validated by MiddleBrick’s Authentication and BOLA/IDOR checks, which map findings to compliance frameworks such as PCI-DSS and SOC2.