Zone Transfer in Axum with Cockroachdb

A zone transfer in Axum with Cockroachdb can occur when a DNS or service discovery integration is misconfigured, allowing an unauthenticated attacker to enumerate internal endpoints or data partitions. In this setup, Axum routes may expose administrative or debug endpoints that interact with Cockroachdb without enforcing strict access controls. Because middleBrick scans the unauthenticated attack surface, it can detect whether zone transfer–style data exposure is possible through open HTTP handlers or GraphQL introspection that reveals Cockroachdb node information.

For example, if an Axum application defines a route like /debug/peers that queries Cockroachdb’s internal SQL tables (e.g., crdb_internal.gossip_table) without authentication, middleBrick will flag this as a BOLA/IDOR and Data Exposure finding. Attackers can leverage this to map the cluster topology, infer tenant boundaries, or extract metadata that assists in further exploitation. The risk is compounded when Cockroachdb is reachable directly from the web layer due to overly permissive firewall rules or missing mTLS, enabling unauthenticated queries that should be restricted to service-to-service communication only.

middleBrick identifies these patterns by correlating OpenAPI/Swagger specs (with full $ref resolution) against runtime behavior. If the spec defines a route that accepts parameters used to construct Cockroachdb SQL queries without validating caller permissions, the scan reports a high-severity finding. Real-world parallels include CVE-like scenarios where debug endpoints inadvertently allow zone transfer–style data leakage, violating the OWASP API Top 10 for Broken Object Level Authorization and exposing sensitive infrastructure details.

To remediate zone transfer risks in Axum when integrating with Cockroachdb, enforce strict authorization on all routes that interact with the database. Use middleware to validate requests before constructing SQL queries, and ensure that endpoints never expose internal cluster metadata.

1. Axum middleware to enforce authentication and tenant scoping

use axum::{routing::get, Router, Extension, http::StatusCode};
use cockroachdb_rs::Connection;
use std::sync::Arc;

struct TenantGuard {
    allowed_tenants: Vec,
}

async fn debug_peers_handler(
    Extension(guard): Extension>,
    // Extract tenant identifier from auth context, not from user input
    auth_tenant: String,
) -> Result {
    if !guard.allowed_tenants.contains(&auth_tenant) {
        return Err((StatusCode::FORBIDDEN, "Unauthorized tenant".into()));
    }
    // Safe: tenant validated before any DB interaction
    let conn = Connection::connect("postgresql://user:pass@localhost:26257/db?sslmode=require")
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
    // Use parameterized queries; never interpolate tenant input into SQL string
    let rows = conn
        .query("SELECT peer_id, status FROM crdb_internal.gossip_table WHERE tenant_id = $1", &[&auth_tenant])
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;
    // Return only non-sensitive fields
    Ok(serde_json::to_string(&rows).unwrap_or_default())
}

fn app() -> Router {
    let guard = Arc::new(TenantGuard { allowed_tenants: vec!["tenant_a".into(), "tenant_b".into()] });
    Router::new()
        .route("/debug/peers", get(debug_peers_handler))
        .layer(Extension(guard))
}

2. Cockroachdb SQL hygiene and least privilege

• Use role-based access control (RBAC) in Cockroachdb to restrict the web application user to read-only on non-sensitive system tables.
• Revoke public access to crdb_internal and information_schema for application roles.

-- Example Cockroachdb role setup (run via migration tool, not from Axum)
CREATE ROLE web_reader;
GRANT SELECT ON TABLE [your_app_tables] TO web_reader;
DENY SELECT ON SCHEMA crdb_internal TO web_reader;
DENY SELECT ON SCHEMA information_schema TO web_reader;

3. Disable introspection and debug routes in production

Ensure that routes like /debug/peers are omitted from the OpenAPI spec in production builds or are protected by mTLS. middleBrick’s CLI can verify this by scanning the published spec and runtime endpoints to confirm that sensitive routes are not exposed.

With the Pro plan, you can enable continuous monitoring so that any regression exposing Cockroachdb metadata triggers alerts in GitHub Actions or Slack, preventing zone transfer–style leaks before they reach production.