This guide provides guidance on best practices for a production hardened deployment of Vault. The recommendations are based on the security model and focus on defense in depth.
Apply When Possible! This guide is meant to provide guidance for an ideal deployment of Vault, not to document requirements. It is entirely possible to use Vault without applying any of the following recommendations. These are best practice recommendations that should be applied when possible and practical.
End-to-End TLS. Vault should always be used with TLS in production. If intermediate load balancers or reverse proxies are used to front Vault, they should not terminate TLS. This way traffic is always encrypted in transit to Vault and minimizes risks introduced by intermediate layers.
Single Tenancy. Vault should be the only main process running on a machine. This reduces the risk that another process running on the same machine is compromised and can interact with Vault. Similarly, running on bare metal should be preferred to a VM, and a VM preferred to a container. This reduces the surface area introduced by additional layers of abstraction and other tenants of the hardware. Both VM and container based deployments work, but should be avoided when possible to minimize risk.
Firewall traffic. Vault listens on well known ports, use a local firewall to restrict all incoming and outgoing traffic to Vault and essential system services like NTP. This includes restricting incoming traffic to permitted subnets and outgoing traffic to services Vault needs to connect to, such as databases.
Disable SSH / Remote Desktop. When running a Vault as a single tenant application, users should never access the machine directly. Instead, they should access Vault through its API over the network. Use a centralized logging and telemetry solution for debugging. Be sure to restrict access to logs as need to know.
Disable Swap. Vault encrypts data in transit and at rest, however it must still have sensitive data in memory to function. Risk of exposure should be minimized by disabling swap to prevent the operating system from paging sensitive data to disk. Vault attempts to "memory lock" to physical memory automatically, but disabling swap adds another layer of defense.
Don't Run as Root. Vault is designed to run as an unprivileged user, and there is no reason to run Vault with root or Administrator privileges, which can expose the Vault process memory and allow access to Vault encryption keys. Running Vault as a regular user reduces its privilege. Configuration files for Vault should have permissions set to restrict access to only the Vault user.
Turn Off Core Dumps. A user or administrator that can force a core dump and has access to the resulting file can potentially access Vault encryption keys. Preventing core dumps is a platform-specific process; on Linux setting the resource limit
0disables core dumps. This can be performed by process managers and is also exposed by various shells; in Bash
ulimit -c 0will accomplish this.
Immutable Upgrades. Vault relies on an external storage backend for persistence, and this decoupling allows the servers running Vault to be managed immutably. When upgrading to new versions, new servers with the upgraded version of Vault are brought online. They are attached to the same shared storage backend and unsealed. Then the old servers are destroyed. This reduces the need for remote access and upgrade orchestration which may introduce security gaps.
Avoid Root Tokens. Vault provides a root token when it is first initialized. This token should be used to setup the system initially, particularly setting up auth methods so that users may authenticate. We recommend treating Vault configuration as code, and using version control to manage policies. Once setup, the root token should be revoked to eliminate the risk of exposure. Root tokens can be generated when needed, and should be revoked as soon as possible.
Enable Auditing. Vault supports several auditing backends. Enabling auditing provides a history of all operations performed by Vault and provides a forensics trail in the case of misuse or compromise. Audit logs securely hash any sensitive data, but access should still be restricted to prevent any unintended disclosures.
Upgrade Frequently. Vault is actively developed, and updating frequently is important to incorporate security fixes and any changes in default settings such as key lengths or cipher suites. Subscribe to the Vault mailing list and GitHub CHANGELOG for updates.
Configure SELinux / AppArmor. Using additional mechanisms like SELinux and AppArmor can help provide additional layers of security when using Vault. While Vault can run on many operating systems, we recommend Linux due to the various security primitives mentioned here.
Restrict Storage Access. Vault encrypts all data at rest, regardless of which storage backend is used. Although the data is encrypted, an attacker with arbitrary control can cause data corruption or loss by modifying or deleting keys. Access to the storage backend should be restricted to only Vault to avoid unauthorized access or operations.
Disable Shell Command History. You may want the
vaultcommand itself to not appear in history at all. Refer to additional methods for guidance.
Tweak ulimits. It is possible that your Linux distribution has strict process
ulimits. Consider to review
ulimitsfor maximum amount of open files, connections, etc. before going into production; they may need increasing.
Docker Containers. To leverage the "memory lock" feature inside the Vault container you will likely need to use the
overlayfs2or another supporting driver.