Dns Cache Poisoning in Hanami with Cockroachdb

DNS cache poisoning can affect Hanami applications that rely on CockroachDB for persistence when the runtime environment or system configuration allows a network attacker to inject false DNS records. In Hanami, service components such as database connection establishment may perform hostname resolution, and if the operating system or intermediate resolver caches a spoofed response for a CockroachDB server hostname, subsequent connections can be directed to a malicious host. This combination becomes exploitable when Hanami services run in environments where DNS responses are not strictly validated, such as containers sharing a host resolver or systems using a vulnerable recursive resolver.

With CockroachDB, the risk is not in CockroachDB’s wire protocol but in the initial hostname-to-IP resolution used by Hanami’s database client libraries. If an attacker can poison the cache for the CockroachDB node hostname (or the load balancer in front of it), Hanami may open a TLS connection or send credentials to an attacker-controlled endpoint. This can lead to credential theft, data interception, or insertion of malicious statements into SQL execution streams. The exposure is amplified if Hanami applications embed database hostnames in configuration that is resolved at runtime rather than using static IPs or strict certificate pinning.

Key conditions specific to this stack include: Hanami services making DNS queries during application boot or per-request database connection setup; CockroachDB hostnames being dynamically configured via environment variables or service discovery; and the absence of strict Transport Layer Security (TLS) server certificate validation that would otherwise mitigate man-in-the-middle (MITM) effects after resolution. MiddleBrick scans can surface such risks by identifying unauthenticated attack surfaces and flagging missing input validation and encryption concerns in the API surface that interacts with backend data stores.

Remediation focuses on ensuring deterministic network paths and strict verification of endpoints in Hanami applications that use CockroachDB. Prefer static IP addresses or tightly controlled DNS zones with DNSSEC enabled for CockroachDB nodes. When hostnames must be used, configure the operating system or container runtime to use a trusted, recursive resolver that rejects unsigned DNS responses and to disable cache poisoning-prone features such as DNS-based service discovery for database endpoints.

In Hanami, you can enforce certificate validation and avoid runtime hostname resolution variability by configuring the database connection with explicit parameters and verifying server identity. Below is a concrete Hanami setup using the rom-repository and CockroachDB Ruby driver, where the connection URI is built from fixed values and strict SSL settings are enforced:

# config/initializers/database.rb
require "uri"

# Use fixed IPs or tightly controlled hostnames; avoid dynamic resolution in production
db_host = ENV.fetch("COCKROACHDB_HOST", "10.0.3.10")
db_port = ENV.fetch("COCKROACHDB_PORT", "26257")
db_name = ENV.fetch("COCKROACHDB_DATABASE", "myapp")
db_user = ENV.fetch("COCKROACHDB_USER", "appuser")
db_password = ENV.fetch("COCKROACHDB_PASSWORD", "strongsecret")

# Enforce TLS with explicit certificate verification
uri = URI::Generic.build(
  scheme: "postgresqls",
  host: db_host,
  port: db_port,
  user: db_user,
  password: db_password
)

# Pass sslrootcert and sslcert/sslkey via connection parameters if required
conn_string = uri.to_s + "?sslmode=verify-full&sslrootcert=/etc/ssl/certs/ca_cockroach.pem"

# ROM repository configuration with strict settings
require "rom"
require "rom/repository"

DB = ROM.container(
  :sql,
  conn_string,
  connect:
    sslmode: "verify-full",
    sslrootcert: "/etc/ssl/certs/ca_cockroach.pem",
    sslcert: "/etc/ssl/certs/client.pem",
    sslkey: "/etc/ssl/certs/client.key"
)

# Define a simple relation and repository mapping
require "rom/sql/repository"
class UsersRepository < ROM::Repository[:sql]
  relations :users
  commands :create, :update, :delete
end

users_repo = UsersRepository.new(DB[:users])

Additionally, integrate middleBrick checks into your workflow by scanning the public API endpoints your Hanami service exposes. Use the CLI to run scans from the terminal: middlebrick scan <url>, or add the GitHub Action to your CI/CD pipeline to fail builds if the risk score drops below your chosen threshold. For continuous assurance, the Pro plan supports scheduled scans and alerts, while the MCP Server enables scanning APIs directly from AI coding assistants within your development environment.