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Docusign API Key

A Docusign API Key is a credential used to authenticate and authorize applications to interact with the Docusign API, which provides electronic signature services. This API key allows developers to integrate Docusign's functionality into their applications, enabling features such as sending documents for signature, managing envelopes, and retrieving signed documents. Exposure of this API key is a significant security concern because it can grant unauthorized access to sensitive documents and operations within the Docusign platform.

How Does It Look​

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

  • Environment variables:

    export DOCUSIGN_API_KEY="d0cUs1gnAp1K3yExAmPl3"

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

    {
      "docusign": {
        "apiKey": "d0cUs1gnAp1K3yExAmPl3"
      }
    }

  • Code snippets:

    docusign_api_key = "d0cUs1gnAp1K3yExAmPl3"

  • Connection strings:

    docusign://apikey:d0cUs1gnAp1K3yExAmPl3@api.docusign.net

Severity​

  • 🔴 Critical

The severity of a Docusign API key exposure is critical because it can provide full access to the Docusign account associated with the key. This includes the ability to send, modify, and delete documents, potentially leading to unauthorized transactions and data breaches. The blast radius is significant as it can affect all documents and operations within the account.

What Can an Attacker Do?​

With immediate access to a Docusign API key, an attacker can perform a range of malicious activities:

An attacker can immediately access the Docusign account and perform actions such as sending unauthorized documents for signature or accessing sensitive documents.

Key actions an attacker can perform:

  • Send fraudulent documents: Initiate document signing processes (if the credential has send permissions)
  • Access sensitive documents: Retrieve confidential documents and data (if read access is enabled)
  • Modify document workflows: Alter document routing and approval processes (if modify permissions are granted)
  • Delete documents: Remove critical documents from the system (if delete permissions are available)

Additionally, an attacker could escalate their access by exploiting other vulnerabilities within the Docusign account or use the compromised API key to move laterally to other integrated systems.

Real-World Impact​

The exposure of a Docusign API key poses significant business risks, including:

The primary impact is the unauthorized access to sensitive documents and the potential for fraudulent transactions.

Potential consequences include:

  • Data Exposure: Confidential client or business documents (if the credential has read access to sensitive data)
  • Financial Loss: Unauthorized transactions or document processing fees (if billing/resource creation is permitted)
  • Operational Disruption: Interruption of document workflows and business processes (if the attacker has delete/modify permissions)
  • Reputational Damage: Loss of client trust and brand integrity

In the worst-case scenario, the exposure could lead to cascading effects such as legal liabilities and regulatory penalties due to unauthorized access and data breaches.

Prerequisites for Exploitation​

To exploit a Docusign API key, an attacker needs:

  • Network access: Ability to send requests to the Docusign API endpoint
  • Additional context: Knowledge of the Docusign account structure and endpoints
  • Rate limits: Awareness of any API rate limits or restrictions that might impede exploitation

How to Verify If It's Active​

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

curl -H "Authorization: Bearer [API_KEY]" https://api.docusign.net/v2.1/accounts

Valid credential response: A successful response will include account details and metadata.

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

Detection Patterns​

Common Variable Names:

  • DOCUSIGN_API_KEY
  • DOCUSIGN_KEY
  • DOCUSIGN_SECRET
  • API_KEY_DOCUSIGN
  • DOCUSIGN_TOKEN
  • DOCUSIGN_ACCESS_KEY

File Locations:

  • .env
  • config.json
  • settings.yaml
  • credentials.txt
  • docusign_config.py

Regex Pattern:

docusign[a-zA-Z0-9]{20,40}

Remediation Steps​

  1. Revoke immediately - Go to Docusign Admin > API and Keys > Delete the compromised API key
  2. Audit access logs - Review Docusign audit logs for unauthorized document access or transactions 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 Docusign Admin with least-privilege permissions
  5. Update dependent systems - Deploy the new credential to all applications and update CI/CD pipelines securely
  6. Harden access controls - Enable IP allowlisting in Docusign and require multi-factor authentication for 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​