API / Vault interview questions
Vault is a tool for securely accessing secrets. A secret is anything that you want to tightly control access to, such as API keys, passwords, or certificates. Vault provides a unified interface to any secret, while providing tight access control and recording a detailed audit log.
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Secure Secret Storage: Arbitrary key/value secrets can be stored in Vault. Vault encrypts these secrets prior to writing them to persistent storage, so gaining access to the raw storage isnt enough to access your secrets.
Dynamic Secrets: Vault can generate secrets on-demand for some systems, such as AWS or SQL databases. For example, when an application needs to access an S3 bucket, it asks Vault for credentials, and Vault will generate an AWS keypair with valid permissions on demand. After creating these dynamic secrets, Vault will also automatically revoke them after the lease is up.
Data Encryption: Vault can encrypt and decrypt data without storing it. This allows security teams to define encryption parameters and developers to store encrypted data in a location such as SQL without having to design their own encryption methods.
Leasing and Renewal: All secrets in Vault have a lease associated with them. At the end of the lease, Vault will automatically revoke that secret. Clients are able to renew leases via built-in renew APIs.
Revocation: Vault has built-in support for secret revocation. Vault can revoke not only single secrets, but a tree of secrets, for example, all secrets read by a specific user, or all secrets of a particular type. Revocation assists in key rolling as well as locking down systems in the case of an intrusion.
Network Security: Ensure that the communication between the client and the Vault server is encrypted and that the network is properly secured. This can be done by using TLS certificates and ensuring the network is isolated from the internet.
Access control: Vault should be configured with appropriate access controls to ensure that only authorized personnel can access sensitive data. This can be done by using authentication and authorization policies, such as user authentication, token-based authentication, and policy-based access control.
Data encryption: Vault uses encryption to protect the sensitive data it stores. Ensure that the encryption keys are properly managed and that the encryption algorithm used is strong and secure.
Disaster recovery: Vault should have a disaster recovery plan in place in case of a failure or data loss. This includes regular backups, offsite storage of backups, and a well-defined procedure for restoring data in case of a disaster.
Logging and auditing: Monitor the activity of Vault and log all access attempts and changes to the data. This information can be used for auditing purposes and for detecting security breaches.
Physical security: The physical security of the Vault server should be ensured. This includes controlling access to the server, ensuring that the server is properly secured, and monitoring the server for unauthorized access attempts.
Vault uses policies to control the behavior of clients and to provide Role Based Access Control (RBAC) by specifying access privileges for users. Vault creates a root policy during initialization and makes this policy available to the superuser only. The root policy allows the superuser to enable secret engines, define policies, and configure authentication methods.
Vault Transit Secret Engine provides encryption as a service. By storing encryption keys in Vault, it allows you to encrypt/decrypt and sign/verify arbitrary pieces of data. This functionality has several advantages, such as limited key exposure, so the keys never leave the Vault.
