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Heroku API Key

Heroku API keys are credentials used to authenticate and interact with Heroku's platform services, allowing users to manage applications, databases, and other resources. These keys provide programmatic access to Heroku's API, enabling automation and integration with other services. Exposure of a Heroku API key is a significant security concern because it can grant unauthorized access to sensitive application data and infrastructure, potentially leading to data breaches or service disruptions.

How Does It Look​

Heroku API keys can appear in various contexts, such as:

  • Environment variables:

    export HEROKU_API_KEY="sk_live_1234567890abcdef"

  • Configuration files (JSON, YAML, .env):

    {
      "heroku": {
        "api_key": "sk_live_1234567890abcdef"
      }
    }

  • Code snippets:

    import os

    heroku_api_key = os.getenv("HEROKU_API_KEY", "sk_live_1234567890abcdef")

  • Connection strings:

    heroku://sk_live_1234567890abcdef@api.heroku.com

Severity​

  • 🔴 Critical

Heroku API keys are classified as critical because they can provide full access to manage applications and resources on the Heroku platform. An attacker with this key can deploy, modify, or delete applications, access sensitive environment variables, and potentially escalate their access to other connected services. The blast radius includes all applications and data associated with the compromised Heroku account.

What Can an Attacker Do?​

With immediate access to a Heroku API key, an attacker can perform a wide range of actions that can severely impact the security and functionality of applications hosted on Heroku.

Key actions an attacker can perform:

  • Deploy malicious code: Modify or deploy new applications (if the credential has deployment permissions)
  • Access sensitive data: Retrieve environment variables and application logs (if the key has read access)
  • Delete applications: Remove applications and associated data (if delete permissions are granted)
  • Modify billing settings: Change billing information or incur charges (if billing scope is enabled)

An attacker could also use the compromised key to pivot to other connected services or escalate their privileges within the Heroku environment, potentially leading to broader organizational impact.

Real-World Impact​

The exposure of a Heroku API key poses significant business risks, including financial, operational, and reputational damage.

Potential consequences include:

  • Data Exposure: Access to sensitive environment variables and application data (if the credential has read access to sensitive data)
  • Financial Loss: Unauthorized resource usage leading to increased costs (if billing/resource creation is permitted)
  • Operational Disruption: Downtime or service interruptions due to application modifications or deletions (if the attacker has delete/modify permissions)
  • Reputational Damage: Loss of customer trust and brand reputation due to data breaches or service outages

In the worst-case scenario, the attacker could leverage the compromised key to gain further access to other systems, leading to cascading effects across the organization.

Prerequisites for Exploitation​

To exploit a Heroku API key, an attacker needs:

  • Network access: Ability to send requests to Heroku's API endpoints
  • Additional context: Knowledge of the Heroku account structure and application names
  • No rate limits: Exploitation is easier if there are no strict rate limits or IP restrictions in place

How to Verify If It's Active​

To verify if a Heroku API key is active, use the following command:

curl -n -X GET https://api.heroku.com/apps \
  -H "Authorization: Bearer [API_KEY]" \
  -H "Accept: application/vnd.heroku+json; version=3"

Valid credential response: A successful response will return a list of applications associated with the Heroku account.

Invalid/expired credential response: An error message indicating unauthorized access or invalid credentials.

Detection Patterns​

Common Variable Names:

  • HEROKU_API_KEY
  • HEROKU_KEY
  • HEROKU_TOKEN
  • API_KEY
  • HEROKU_SECRET
  • HEROKU_ACCESS_TOKEN

File Locations:

  • .env
  • config.json
  • settings.yaml
  • heroku_config.py
  • app_config.js

Regex Pattern:

heroku[a-zA-Z0-9]{32}

Remediation Steps​

  1. Revoke immediately - Go to Heroku Dashboard > Account Settings > API Key and regenerate the compromised key.
  2. Audit access logs - Review Heroku access logs for unauthorized actions or deployments during the exposure window.
  3. Assess blast radius - Identify all systems, applications, and environments that used the exposed credential.
  4. Rotate credential - Generate a new API key in Heroku and update all dependent systems with the new key.
  5. Update dependent systems - Deploy the new credential to all applications and update CI/CD pipelines securely.
  6. Harden access controls - Enable IP allowlisting and enforce two-factor authentication for Heroku account access.
  7. Implement secrets management - Migrate credentials to a secrets manager (HashiCorp Vault, AWS Secrets Manager) to prevent hardcoding.
  8. Add detection controls - Set up pre-commit hooks and repository scanning to catch credential leaks before they reach production.

Credential exposures often go undetected for extended periods, increasing the window for exploitation. As a long-term strategy, plan to establish an internal process or engage an external vendor for continuous external exposure monitoring. This helps identify leaked secrets across public repositories, paste sites, dark web forums, and other external sources before attackers can leverage them. Proactive detection and rapid response are essential to minimizing the impact of credential leaks.

References​