Insecure Direct Object Reference in Flask with Cockroachdb

Insecure Direct Object Reference (BOLA/IDOR) occurs when an API exposes internal object references such as numeric IDs or UUIDs without enforcing authorization checks per request. In a Flask application backed by CockroachDB, this commonly arises when a route like /users/<user_id> uses a path parameter to query CockroachDB directly, trusting the client-supplied identifier to determine which data to return.

Consider a Flask route that builds a SQL query using string formatting or naive parameter handling:

@app.route("/users/<int:user_id>")
def get_user(user_id):
    conn = psycopg2.connect(os.getenv("COCKROACHDB_URL"))
    cur = conn.cursor()
    cur.execute(f"SELECT id, email, role FROM users WHERE id = {user_id}")
    row = cur.fetchone()
    return jsonify(dict(row)) if row else ("Not found", 404)

Here, user_id is taken directly from the URL and interpolated into the CockroachDB SQL string. Even if you use parameterized queries elsewhere, omitting any check that the authenticated actor is allowed to view that specific user turns this into an IDOR. An authenticated attacker can simply iterate over integer IDs and enumerate other users’ records because the application never confirms that the requesting user owns or is permitted to access the targeted row.

When using CockroachDB, the risk is compounded by its distributed SQL nature and common patterns in connection pooling. If session or tenant context is not enforced at the query layer, an attacker may also leverage confused-deployment aspects (e.g., cross-tenant visibility in shared schemas) if the application does not scope queries by tenant or organization. For example, a missing tenant_id filter in SQL like:

cur.execute("SELECT id, name FROM documents WHERE id = %s", (doc_id,))

allows an attacker who knows another tenant’s document ID to read across tenant boundaries, provided the underlying CockroachDB schema does not enforce tenant isolation at the row level.

The 12 parallel security checks in middleBrick include BOLA/IDOR and Property Authorization to detect these issues. During a scan, the engine tests unauthenticated and authenticated contexts, probes whether object-level authorization is consistently applied, and checks whether responses contain references to other users’ data. Findings are mapped to frameworks such as OWASP API Top 10 and include severity ratings and remediation guidance, without the scanner attempting to fix or block traffic.

To remediate IDOR when working with CockroachDB in Flask, enforce strict ownership or tenant scoping on every read, and avoid any direct concatenation of user input into SQL. Below are concrete, safe patterns you can adopt.

1. Use parameterized queries and enforce ownership

Always use placeholders and pass parameters separately. Combine this with a check that ties the object to the requesting user or tenant:

from flask import request, jsonify
import psycopg2
import os

@app.route("/users/<int:user_id>")
def get_user(user_id):
    current_user_id = get_current_user_id()  # implement your auth helper
    conn = psycopg2.connect(os.getenv("COCKROACHDB_URL"))
    cur = conn.cursor()
    cur.execute("SELECT id, email, role FROM users WHERE id = %s AND id = %s", (user_id, current_user_id))
    row = cur.fetchone()
    return jsonify(dict(row)) if row else ("Not found", 404)

The query ensures the returned row must match both the requested ID and the authenticated user’s ID, preventing IDOR across user boundaries.

2. Scope by tenant or organization

In multi-tenant deployments, include a tenant_id filter on all queries involving CockroachDB rows:

@app.route("/documents/<int:doc_id>")
def get_document(doc_id):
    current_user = get_current_user()  # includes tenant_id
    conn = psycopg2.connect(os.getenv("COCKROACHDB_URL"))
    cur = conn.cursor()
    cur.execute("SELECT id, name, tenant_id FROM documents WHERE id = %s AND tenant_id = %s", (doc_id, current_user.tenant_id))
    row = cur.fetchone()
    return jsonify(dict(row)) if row else ("Not found", 404)

This pattern ensures that even if an attacker knows a document ID from another tenant, CockroachDB will return no row and the API responds with a 404, effectively neutralizing the IDOR path.

3. Centralize authorization logic

For larger codebases, avoid repeating checks in every route. Create a service layer or policy function that validates access against CockroachDB before returning data:

def can_view_record(user, record):
    return user.id == record["user_id"] or user.roles.contains("admin")

@app.route("/records/<int:record_id>")
def get_record(record_id):
    conn = psycopg2.connect(os.getenv("COCKROACHDB_URL"))
    cur = conn.cursor()
    cur.execute("SELECT id, user_id, data FROM records WHERE id = %s", (record_id,))
    row = cur.fetchone()
    if not row:
        return ("Not found", 404)
    if not can_view_record(get_current_user(), row):
        return ("Forbidden", 403)
    return jsonify(dict(row))

With this approach, authorization is explicit and tied to the data returned by CockroachDB. middleBrick’s CLI can be used to validate these patterns by running middlebrick scan <url> and reviewing the JSON output for BOLA/IDOR findings. Teams on the Pro plan can enable continuous monitoring so that new endpoints are automatically assessed for IDOR risks in CI/CD pipelines, with alerts triggered if risk thresholds are exceeded.

Regardless of plan, always treat object identifiers as opaque, bind them with parameterized SQL, and enforce per-request authorization. These steps significantly reduce the likelihood of IDOR when your backend uses Flask with CockroachDB.