Api Key Exposure in Flask with Cockroachdb

When a Flask application connects to Cockroachdb using an API key or connection string that is hardcoded, logged, or exposed in error messages, the database credentials become an API surface. In a black-box scan, middleBrick tests unauthenticated endpoints and observes whether any response reveals database connection details. For example, a route that constructs SQL strings by concatenating user input can produce verbose errors that include the connection origin, inadvertently disclosing the Cockroachdb API key or cluster host.

Consider a typical misconfiguration: the Flask app imports os.getenv("COCKROACH_URL") and uses it directly with a database driver. If the application does not handle exceptions carefully, a 500 response might return a traceback containing the full connection URI, including the embedded API key. middleBrick’s Data Exposure and Input Validation checks would flag this as a finding because the unauthenticated probe can trigger an error that leaks the key. Additionally, if the API key is passed in an HTTP header or query parameter and the endpoint reflects it in JSON or HTML without proper sanitization, the key can be exfiltrated through an SSRF or insecure consumption path.

Another scenario involves OpenAPI specs that accidentally document the API key as a query parameter. middleBrick’s spec analysis resolves all $ref chains and cross-references runtime behavior with the declared schema. If the spec includes a parameter named api_key in a path that is reachable without authentication, the scanner reports an insecure consumption finding. Cockroachdb-specific metadata in error objects—such as the database name or node ID—can further aid an attacker in crafting targeted requests. The combination of a Flask route that does not enforce strict input validation and a Cockroachdb driver that propagates detailed errors increases the likelihood that an API key is exposed during normal operation.

middleBrick’s LLM/AI Security checks are not designed to detect database credential leakage, but its Data Exposure and Input Validation modules identify patterns where sensitive values appear in responses. The scanner runs 12 checks in parallel, including Authentication, Property Authorization, and Unsafe Consumption, to surface endpoints that should not disclose connection details. By correlating spec definitions with runtime outputs, middleBrick can pinpoint whether an API key is present in logs, error payloads, or client-side representations.

To prevent API key exposure, store the Cockroachdb connection string outside the application code and ensure that any usage does not propagate sensitive values into responses. Use environment variables loaded at runtime and avoid constructing SQL strings with string interpolation. Below are concrete code examples for a Flask app connecting to Cockroachdb securely.

import os
from flask import Flask, jsonify, request
import psycopg2
from psycopg2 import sql

app = Flask(__name__)

# Load from environment; do not commit this value to source control
COCKROACH_URL = os.getenv("COCKROACH_URL")
if not COCKROACH_URL:
    raise RuntimeError("COCKROACH_URL environment variable is required")

@app.route("/users/<int:user_id>")
def get_user(user_id):
    conn = None
    try:
        conn = psycopg2.connect(COCKROACH_URL)
        with conn.cursor() as cur:
            # Use SQL composition to avoid injection; never concatenate raw input
            query = sql.SQL("SELECT id, name FROM users WHERE id = %s")
            cur.execute(query, (user_id,))
            row = cur.fetchone()
            if row:
                return jsonify({"id": row[0], "name": row[1]})
            return jsonify({"error": "not found"}), 404
    except psycopg2.Error as e:
        # Return a generic error to avoid leaking connection details
        app.logger.error("Database error: %s", e.pgcode if hasattr(e, 'pgcode') else str(e))
        return jsonify({"error": "internal server error"}), 500
    finally:
        if conn:
            conn.close()

if __name__ == "__main__":
    app.run()

This example avoids including the connection URI in any response body or log message that could be returned to the client. The error handling returns a generic 500 status without exposing stack traces that might contain the Cockroachdb API key. middleBrick’s Input Validation and Data Exposure checks would validate that no sensitive values appear in responses and that error messages are sanitized.

Additionally, restrict the permissions of the Cockroachdb user to the minimum required by the application. If the API key corresponds to a database role, ensure it cannot be used to read other tenants or configuration tables. middleBrick’s BFLA/Privilege Escalation and Property Authorization checks help verify that endpoints do not exceed necessary privileges. For continuous assurance, use the middleBrick CLI to scan from terminal with middlebrick scan <url> or integrate the GitHub Action to fail builds if a scan detects exposed credentials. The Pro plan adds continuous monitoring so that any regression in exposure is flagged promptly.