Api Key Exposure in Phoenix with Cockroachdb

Api Key Exposure occurs when application code or configuration that contains sensitive credentials is inadvertently accessible to unauthorized parties. In a Phoenix application using Cockroachdb as the database backend, this risk can emerge from several common patterns. Developers may embed database credentials or external service API keys directly in source files, configuration modules, or environment-loading logic that is checked into version control. Phoenix applications often rely on config/runtime.exs and config/prod.exs to provide runtime configuration, and if these files contain hardcoded keys or if environment variables are not properly restricted, the keys can be exposed through logs, error pages, or insecure dependency deployments.

When Cockroachdb is used in this context, the exposure risk is compounded by the distributed nature of the database. A Phoenix app connects to Cockroachdb via connection strings or URL-based configurations, and if these strings are logged during startup or included in telemetry, the credentials can be captured. For example, a connection string like postgresql://user:password@host:26257/dbname?sslmode=require may be printed to the console if the application logs connection attempts at the :info level. In a multi-node Cockroachdb cluster, each node maintains its own authentication handshake, and if any node’s logs or metrics are exposed, embedded credentials become accessible to anyone with access to those observability surfaces.

Additionally, in a Phoenix deployment pipeline, API keys used to authenticate with external services (such as cloud storage or payment gateways) may be injected into the runtime environment via configuration providers. If these providers are improperly scoped or if fallback defaults are used during local development, the keys may leak into test or staging environments. Because Cockroachdb often serves as the primary data store, any process that queries or migrates the database may inadvertently log sensitive context, such as query parameters or connection metadata, which can include authorization tokens or derived keys. An attacker who gains access to logs, crash dumps, or monitoring dashboards can then use these exposed keys to escalate privileges or move laterally across services.

The combination of Phoenix’s dynamic configuration system and Cockroachdb’s client driver behavior increases the likelihood of accidental exposure during error handling. If a Phoenix endpoint fails to establish a Cockroachdb connection due to invalid credentials, the resulting exception may include the full connection string in the error report. Without proper sanitization, these exceptions can be rendered in HTML error pages or sent to external monitoring tools, making the credentials visible to unauthenticated users or third-party services. This scenario aligns with common findings in scans run by tools like middleBrick, which detect exposed credentials through pattern matching and runtime analysis of unauthenticated endpoints.

middleBrick scans such an environment by analyzing the OpenAPI specification and runtime behavior without authentication, identifying endpoints that may leak sensitive data. The scanner checks for insecure logging practices, improper error handling, and configuration exposure that could lead to Api Key Exposure. Its findings map to frameworks such as OWASP API Top 10 and SOC2, highlighting risks specific to database integrations and external service dependencies. For teams using middleBrick’s CLI or GitHub Action, these issues can be caught before deployment, preventing credentials from reaching production environments.

To remediate Api Key Exposure in a Phoenix application using Cockroachdb, focus on secure configuration management, strict logging controls, and safe error handling. The following code examples demonstrate how to implement these practices using Elixir’s built-in tools and the Ecto adapter for Cockroachdb.

1. Secure Configuration with Runtime Secrets

Never hardcode credentials in configuration files. Instead, use system environment variables and ensure they are loaded securely at runtime. In config/runtime.exs, reference environment variables directly without providing fallback values that could leak defaults.

# config/runtime.exs
import Config

if config_env() == :prod do
  database_url = System.get_env("DATABASE_URL") || raise "DATABASE_URL environment variable is missing"
  
  config :my_app, MyApp.Repo,
    url: database_url,
    pool_size: 10,
    ssl: ["sslmode": "require"],
    parameters: ["application_name": "phoenix-api"]
end

Ensure that DATABASE_URL follows the Cockroachdb-compatible format:

postgresql://user:password@host1:26257,host2:26257/dbname?sslmode=require&sslrootcert=root.crt

2. Disable Sensitive Logging in Ecto and Phoenix

Prevent connection strings and query parameters from appearing in logs by configuring Ecto and Logger levels appropriately. In config/prod.exs, set the Ecto log level to :warning and avoid logging query parameters.

# config/prod.exs
import Config

config :logger, level: :info

config :my_app, MyApp.Repo,
  log: [loggers: [{Logger, level: :warn}]]

Additionally, sanitize any exception reports that might include connection details. Override Phoenix.Controller.action_call/2 or use a custom plug to redact sensitive parameters from error messages.

3. Secure Error Handling and Connection Initialization

Handle database connection errors without exposing stack traces or credentials. Use guarded clauses to catch authentication failures and return generic error responses.

# lib/my_app_web/plugs/sanitize_errors.ex
defmodule MyAppWeb.SanitizeErrors do
  import Plug.Conn

  def init(opts), do: opts

  def call(conn, _opts) do
    try do
      conn
    rescue
      e in Postgrex.Error ->
        # Log full error internally, but return safe message externally
        Logger.warning("Database error: #{inspect(e.message)}")
        send_resp(conn, 500, "Internal server error")
    end
  end
end

4. Rotate Keys and Use IAM Integration

Even with secure code, leaked keys must be rotated immediately. Configure Cockroachdb users with limited privileges and use short-lived credentials where possible. If running on a supported cloud provider, integrate with IAM-based authentication instead of static passwords.

-- Example Cockroachdb user setup with minimal privileges
CREATE USER phoenix_app WITH PASSWORD 'strong-random-token';
GRANT SELECT, INSERT ON DATABASE app_production TO phoenix_app;
REVOKE ALL ON DATABASE system FROM phoenix_app;

By combining these code-level practices with regular scans using middleBrick’s Pro plan—which enables continuous monitoring and CI/CD integration—you can detect and prevent Api Key Exposure before it reaches production. The CLI tool allows you to automate checks in scripts, while the GitHub Action can fail builds if credentials are detected in committed code.