Api Key Exposure in Hanami with Redis

When a Hanami application stores API keys in Redis without appropriate safeguards, the combination of an in-memory data store and a Ruby web framework can inadvertently expose sensitive credentials. Redis is often used for caching session data, rate-limiting counters, or temporary storage of service tokens. If Hanami developers write API keys directly into Redis keyspaces without encryption or strict access controls, those keys can be exposed through several realistic paths.

One common pattern is using Redis to cache third-party service tokens that are shared across workers or pods. For example, a Hanami service might push a key into Redis with a predictable key name like api_key:production:payment_gateway. If an attacker gains network access to the Redis instance—via an exposed port, weak firewall rules, or a compromised container—they can read this key using simple commands such as GET api_key:production:payment_gateway. Because Redis does not encrypt data at rest by default in many deployments, the key is stored in plaintext and easily exfiltrated.

Another vector involves log exposure and error handling. If Hanami code rescues Redis connection errors and inadvertently logs the full command arguments, an API key cached in a Redis value might appear in application logs. For instance, passing the key as part of an HSET payload without redaction can result in plaintext secrets in log aggregation systems. Additionally, if the application uses Redis pub/sub to distribute configuration updates, a key published on a channel (e.g., config_updates) can be intercepted by any subscriber with access to that channel.

The unauthenticated attack surface amplifies risk when Redis is exposed to the internet or shared across environments. In cloud deployments, misconfigured security groups or container networking can leave Redis open without password protection. middleBrick scans detect such exposures by testing unauthenticated endpoints and identifying whether Redis responds to commands like INFO or KEYS * without authentication, flagging the API key exposure risk under Data Exposure and Unsafe Consumption checks. This aligns with OWASP API Top 10’s Broken Object Level Authorization and Security Misconfiguration, as well as PCI-DSS requirements around secret management.

Using middleBrick’s scans, teams can identify whether Redis responses reveal sensitive patterns resembling API keys, and the report includes remediation guidance. For production systems, the Pro plan’s continuous monitoring can alert when a scan detects Redis endpoints returning key-like values, enabling rapid response before credentials are leaked. In CI/CD pipelines, the GitHub Action can fail a build if a scan discovers unauthenticated Redis access that could lead to API key exposure, preventing vulnerable configurations from reaching staging or production.

To prevent API key exposure when using Redis with Hanami, apply defense-in-depth measures that combine encryption, strict access controls, and secure coding practices. Below are concrete, realistic code examples that illustrate how to store and interact with API keys safely in a Hanami application backed by Redis.

1. Use Encrypted Storage for Sensitive Values

Instead of storing raw API keys, encrypt them before writing to Redis. Use a robust encryption library such as lockbox or attr_encrypted. The example below uses Lockbox with AES-GCM, a mode that provides authenticated encryption, ensuring confidentiality and integrity.

require 'lockbox
# config/initializers/lockbox.rb
key = File.read('/path/to/encryption-key.key').strip
Lockbox.key = key
lockbox = Lockbox.new(encode: true)

# In a Hanami entity or service object
encrypted_value = lockbox.encrypt('sk_live_abc123xyz')
Redis.current.set('api_key:payment_gateway:encrypted', encrypted_value)

# Retrieval
decrypted = lockbox.decrypt(Redis.current.get('api_key:payment_gateway:encrypted'))
# decrypted == 'sk_live_abc123xyz'

2. Apply Strict Key Naming and Access Patterns

Avoid predictable key names and reduce the impact of a potential leak by namespacing keys with random suffixes and using Redis hashes to group related fields. This limits exposure if an attacker enumerates keys.

# Writing with a namespaced hash and a random suffix
suffix = SecureRandom.hex(4)
key = "api:hash:#{suffix}"
Redis.current.hset(key, 'service', 'payment_gateway')
Redis.current.hset(key, 'encrypted_value', lockbox.encrypt('sk_live_abc123xyz'))
Redis.current.expire(key, 3600) # short TTL

# Reading safely
matches = Redis.current.keys('api:hash:*')
matches.each do |k|
  data = Redis.current.hgetall(k)
  # process securely
end

3. Disable Dangerous Commands and Require Authentication

Configure Redis to disable commands like CONFIG, FLUSHDB, and KEYS in production, and always require a password. In redis.conf or via managed Redis parameter groups, set:

# redis.conf
requirepass your_strong_redis_password
rename-command CONFIG ""
rename-command FLUSHDB ""
rename-command KEYS ""

In Hanami code, always authenticate before connecting:

Redis.new(url: 'redis://:[email protected]:6379/0')

4. Avoid Logging Secrets and Use Environment Variables

Ensure Redis command arguments that contain sensitive data are not logged. Do not interpolate API keys into log messages. Load Redis credentials and keys from environment variables or a secrets manager rather than hardcoding them.

# Bad: potential log exposure
Redis.current.set("key:#{api_key}", 'value')

# Better: keep key names opaque and avoid logging the value
key = "key:#{Digest::SHA256.hexdigest(api_key)[0..12]}"
Redis.current.set(key, 'value')

5. Use Short TTLs and Rotate Keys

Set short expiration times on cached API keys and implement a rotation strategy. This reduces the window of exposure if a key is leaked.

Redis.current.setex('api_key:ephemeral', 300, encrypted_value) # 5 minutes TTL

By combining encryption, restricted command usage, short TTLs, and secure configuration, Hanami applications can mitigate the risk of API key exposure when using Redis. middleBrick’s scans can validate these controls by checking for unauthenticated Redis access, plaintext storage of secrets, and dangerous command exposure, with findings linked to compliance frameworks such as OWASP API Top 10 and PCI-DSS.