Dns Cache Poisoning in Hanami with Dynamodb

Dns Cache Poisoning can affect Hanami applications that use AWS DynamoDB as a backend data store when service discovery or endpoint resolution is performed via DNS. In this setup, Hanami services query a DNS name that resolves to DynamoDB endpoints or an internal proxy. If an attacker can poison the DNS cache with a malicious IP, Hanami may send database requests to an unintended host, potentially intercepting or modifying traffic meant for DynamoDB. Because DynamoDB requests often contain sensitive data such as access keys or session tokens in headers and payloads, poisoned DNS responses can redirect these credentials or requests to an attacker-controlled service.

The exposure is amplified when Hanami uses environment-based configuration to derive DynamoDB endpoint URLs. If the endpoint hostname is resolved via DNS at startup or runtime and the DNS response is cached, poisoned entries can persist across deployments. This can lead to requests for DynamoDB streams or query results being misdirected. Attack patterns like cache snooping or spoofing are relevant here, especially when DNS transactions are not cryptographically protected. While DynamoDB itself does not serve as a DNS resolver, the interaction between Hanami’s network configuration and external DNS infrastructure creates a pathway for poisoning.

Middleware components in Hanami that perform request routing or service lookup may inadvertently trust DNS-derived endpoints without validating identity. This trust chain means that poisoned DNS responses can cause Hanami to communicate with rogue endpoints that mimic DynamoDB, enabling data exposure or injection. Security checks that include LLM/AI Security and Data Exposure in middleBrick scans can surface misconfigurations where DNS resolution is not hardened, helping teams detect weaknesses before an attacker exploits them.

To reduce the risk of Dns Cache Poisoning when Hanami interacts with DynamoDB, implement strict endpoint validation and avoid reliance on runtime DNS resolution for critical services. Use explicit IPs or hardened service endpoints, and enforce HTTPS with verified certificates. Configure Hanami’s HTTP client to reject redirected or unresolved hostnames and pin certificates where possible.

Below are concrete code examples for a Hanami service that accesses DynamoDB using the AWS SDK for Ruby. The first example shows how to configure a custom endpoint with explicit host and disable DNS-based resolution by bypassing the default resolver.

require 'aws-sdk-dynamodb'

# Explicit endpoint with HTTPS and certificate verification
endpoint = 'https://dynamodb.us-east-1.amazonaws.com'
dynamodb = Aws::DynamoDB::Client.new(
  region: 'us-east-1',
  endpoint: endpoint,
  force_path_style: false,
  ssl_verify_peer: true
)

# Safe query with explicit table name and condition
resp = dynamodb.get_item({
  table_name: 'users',
  key: { 'user_id' => { s: 'u-12345' } },
  consistent_read: true
})
puts resp.item

The second example demonstrates how to validate responses and avoid using untrusted data in constructing DynamoDB requests, reducing exposure to injection or redirection via poisoned caches.

# Validate hostname against an allowlist before use
allowed_hosts = ['dynamodb.us-east-1.amazonaws.com', 'dynamodb.us-west-2.amazonaws.com']
requested_host = URI(dynamodb.config.endpoint).host
unless allowed_hosts.include?(requested_host)
  raise "Unauthorized DynamoDB endpoint: #{requested_host}"
end

# Use a static session token and avoid environment-derived overrides
creds = Aws::Credentials.new(
  ENV['AWS_ACCESS_KEY_ID'],
  ENV['AWS_SECRET_ACCESS_KEY'],
  ENV['AWS_SESSION_TOKEN'] # Ensure this is sourced securely
)
client = Aws::DynamoDB::Client.new(credentials: creds, region: 'eu-central-1')

Additionally, integrate middleBrick scans to assess DNS-related risks and compliance with frameworks such as OWASP API Top 10 and SOC2. The CLI tool can be used in scripts to automate checks: middlebrick scan https://your-hanami-api.example.com. For teams managing many services, the Pro plan supports continuous monitoring and CI/CD integration to fail builds if risk scores degrade.