sec-design.md

Okay, let's create a design document for HashiCorp Vault, keeping in mind its purpose and the need for a threat modeling-ready document.

BUSINESS POSTURE

HashiCorp Vault is a secrets management tool. Its primary business purpose is to provide a secure and reliable way for organizations to store, manage, and access sensitive information (secrets) like API keys, passwords, certificates, and encryption keys. It addresses the critical business need to protect sensitive data from unauthorized access, both internal and external. Given its role in securing critical infrastructure, Vault itself must be highly available and resilient.

Business Priorities:

• Security: Protecting sensitive data is paramount.
• Reliability: Vault must be highly available and fault-tolerant. Downtime means applications can't access secrets, potentially causing widespread outages.
• Scalability: Vault needs to scale to handle the demands of large and growing organizations.
• Compliance: Helping organizations meet regulatory compliance requirements (e.g., GDPR, HIPAA, PCI DSS) related to data protection.
• Auditability: Providing a clear audit trail of all secret access and management activities.
• Usability: Offering a user-friendly interface and API for developers and operators.
• Integrations: Seamlessly integrating with other systems and tools in the DevOps ecosystem.

Business Risks:

• Unauthorized Access to Secrets: The most significant risk is a breach that exposes sensitive data. This could lead to financial loss, reputational damage, legal penalties, and operational disruption.
• Data Loss: Loss of secrets due to hardware failure, software bugs, or human error could render applications and systems unusable.
• Insider Threats: Malicious or negligent insiders with access to Vault could compromise secrets.
• Denial of Service: An attack that renders Vault unavailable could cripple dependent systems.
• Misconfiguration: Incorrectly configured Vault deployments could expose vulnerabilities.
• Compliance Violations: Failure to properly manage secrets could lead to non-compliance with relevant regulations.
• Supply Chain Attacks: Vulnerabilities in Vault's dependencies or build process could be exploited.

SECURITY POSTURE

Existing Security Controls (based on the GitHub repository and HashiCorp documentation):

• security control: Access Control Lists (ACLs): Vault uses a policy-based access control system to restrict access to secrets based on identity and role. Implemented within Vault's policy engine.
• security control: Authentication Methods: Supports multiple authentication methods (e.g., username/password, tokens, AppRole, cloud IAM, Kubernetes Service Accounts). Implemented as pluggable authentication backends.
• security control: Encryption in Transit: All communication with Vault is encrypted using TLS. Described in Vault's documentation and configuration options.
• security control: Encryption at Rest: Vault encrypts data before storing it in its storage backend. Implemented using a layered encryption approach with a master key and data encryption keys.
• security control: Auditing: Vault provides detailed audit logs of all requests and responses. Implemented as pluggable audit devices.
• security control: Secret Engines: Vault supports various secret engines (e.g., Key/Value, Transit, PKI, Database) to manage different types of secrets. Implemented as pluggable secret engines.
• security control: Dynamic Secrets: Vault can generate dynamic secrets (e.g., database credentials) on demand, reducing the risk of long-lived credentials. Implemented within specific secret engines.
• security control: Leasing and Renewal: Secrets can be leased for a specific period, and clients must renew the lease to maintain access. Implemented within Vault's core leasing mechanism.
• security control: Revocation: Secrets and tokens can be revoked, immediately invalidating access. Implemented within Vault's core revocation mechanism.
• security control: Response Wrapping: Sensitive data returned by Vault can be wrapped in a single-use token, protecting it from exposure in logs or intermediate systems. Implemented within Vault's cubbyhole response wrapping.
• security control: Multi-factor Authentication (MFA): Supported through various authentication methods and plugins.
• security control: Control Groups: Allow for requiring multiple approvals for sensitive operations.
• security control: Namespaces: Enterprise feature for isolating tenants.

Accepted Risks:

• accepted risk: Complexity of Configuration: Vault is a complex system, and misconfiguration is a potential risk. Mitigation relies on thorough documentation, training, and careful operational procedures.
• accepted risk: Dependency on Storage Backend: Vault's security and availability depend on the chosen storage backend (e.g., Consul, etcd, Raft). Mitigation involves selecting a highly available and secure storage backend and implementing appropriate backup and recovery procedures.
• accepted risk: Single Point of Failure (Unsealed Vault): A newly initialized or unsealed Vault instance represents a single point of failure until it's properly configured for high availability. Mitigation involves following best practices for high availability setup.

Recommended Security Controls:

• Regular Security Audits: Conduct regular security audits of Vault deployments, including penetration testing and vulnerability scanning.
• Principle of Least Privilege: Strictly enforce the principle of least privilege, granting users and applications only the minimum necessary access to secrets.
• Network Segmentation: Isolate Vault servers on a dedicated network segment with strict firewall rules.
• Intrusion Detection and Prevention Systems (IDPS): Deploy IDPS to monitor network traffic and detect malicious activity.
• Security Information and Event Management (SIEM): Integrate Vault audit logs with a SIEM system for centralized security monitoring and alerting.
• Hardware Security Modules (HSMs): Consider using HSMs to protect Vault's master key and enhance the security of cryptographic operations.

Security Requirements:

• Authentication:

  • Support for multiple authentication methods, including strong authentication options like multi-factor authentication.
  • Integration with existing identity providers (e.g., LDAP, Active Directory, cloud IAM).
  • Secure storage and management of authentication credentials.
  • Session management with appropriate timeouts and invalidation mechanisms.

• Authorization:

  • Fine-grained access control based on roles and policies.
  • Support for the principle of least privilege.
  • Ability to define and enforce access control policies for all secrets and operations.
  • Regular review and auditing of access control policies.

• Input Validation:

  • Validate all input to the Vault API and CLI to prevent injection attacks.
  • Sanitize data before using it in internal operations or storing it in the backend.
  • Enforce data type and format restrictions.

• Cryptography:

  • Use strong, industry-standard cryptographic algorithms and protocols (e.g., AES-256, TLS 1.3).
  • Secure key management practices, including key rotation and protection of master keys.
  • Use of HSMs for enhanced security.
  • Protection against known cryptographic attacks (e.g., padding oracle attacks, timing attacks).

DESIGN

C4 CONTEXT

graph LR
    subgraph Vault System
        Vault[("Vault")]
    end
    Developers[("Developers")]
    Operators[("Operators")]
    Applications[("Applications")]
    ExternalSystems[("External Systems\n(e.g., Databases, Cloud Providers)")]
    AuditDevices[("Audit Devices\n(e.g., Syslog, File)")]
    AuthMethods[("Authentication Methods\n(e.g., LDAP, AppRole, Kubernetes)")]
    StorageBackend[("Storage Backend\n(e.g., Consul, Integrated Storage)")]

    Developers --> Vault : Manage secrets, policies
    Operators --> Vault : Manage Vault infrastructure
    Applications --> Vault : Retrieve secrets
    Vault --> ExternalSystems : Generate dynamic secrets, manage PKI
    Vault --> AuditDevices : Send audit logs
    AuthMethods --> Vault : Authenticate users and applications
    Vault --> StorageBackend : Store encrypted data

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Element Descriptions:

• Element:

  • Name: Vault
  • Type: System
  • Description: The core HashiCorp Vault system responsible for managing secrets.
  • Responsibilities: Storing, managing, and providing access to secrets; enforcing access control policies; generating dynamic secrets; auditing access; providing an API and CLI.
  • Security Controls: ACLs, Encryption (in transit and at rest), Auditing, Secret Engines, Leasing, Revocation, Response Wrapping, Authentication Methods.

• Element:

  • Name: Developers
  • Type: User
  • Description: Software developers who use Vault to manage secrets for their applications.
  • Responsibilities: Defining secrets, writing policies, integrating applications with Vault.
  • Security Controls: Authentication, Authorization (via Vault policies).

• Element:

  • Name: Operators
  • Type: User
  • Description: System administrators who manage the Vault infrastructure.
  • Responsibilities: Installing, configuring, monitoring, and maintaining Vault servers.
  • Security Controls: Authentication, Authorization (via Vault policies), MFA.

• Element:

  • Name: Applications
  • Type: System
  • Description: Applications that need to access secrets to function.
  • Responsibilities: Authenticating with Vault, retrieving secrets, using secrets securely.
  • Security Controls: Authentication, Authorization (via Vault policies).

• Element:

  • Name: External Systems
  • Type: System
  • Description: External systems that Vault interacts with, such as databases, cloud providers, and PKI infrastructure.
  • Responsibilities: Providing services that Vault integrates with (e.g., database credentials, cloud resources).
  • Security Controls: Dependent on the specific external system; Vault manages the credentials used to access these systems.

• Element:

  • Name: Audit Devices
  • Type: System
  • Description: Systems that receive audit logs from Vault (e.g., syslog, file, Splunk).
  • Responsibilities: Storing and analyzing audit logs.
  • Security Controls: Secure storage and access control for audit logs.

• Element:

  • Name: Authentication Methods
  • Type: System
  • Description: Systems and methods used to authenticate users and applications with Vault (e.g., LDAP, AppRole, Kubernetes).
  • Responsibilities: Verifying user and application identities.
  • Security Controls: Dependent on the specific authentication method; Vault integrates with these systems securely.

• Element:

  • Name: Storage Backend
  • Type: System
  • Description: The storage backend used by Vault to store encrypted data (e.g., Consul, Integrated Storage, etcd).
  • Responsibilities: Persistently storing Vault data.
  • Security Controls: Encryption at rest (provided by Vault), data replication and backup (provided by the storage backend).

C4 CONTAINER

graph LR
    subgraph Vault System
        VaultAPI[("Vault API")]
        VaultCore[("Vault Core")]
        SecretEngines[("Secret Engines\n(KV, Transit, PKI, etc.)")]
        AuthMethods[("Auth Methods\n(LDAP, AppRole, etc.)")]
        AuditDevices[("Audit Devices\n(Syslog, File, etc.)")]
        StorageBackend[("Storage Backend\n(Consul, Integrated Storage)")]
    end
        Developers --> VaultAPI : Manage secrets, policies
        Operators --> VaultAPI : Manage Vault infrastructure
        Applications --> VaultAPI : Retrieve secrets
        VaultAPI --> VaultCore : Handle API requests
        VaultCore --> SecretEngines : Manage secrets
        VaultCore --> AuthMethods : Authenticate users/apps
        VaultCore --> AuditDevices : Send audit logs
        VaultCore --> StorageBackend : Store encrypted data

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Element Descriptions:

• Element:

  • Name: Vault API
  • Type: Container
  • Description: The entry point for all interactions with Vault.
  • Responsibilities: Handling API requests, validating input, routing requests to Vault Core.
  • Security Controls: TLS encryption, Input validation, Rate limiting.

• Element:

  • Name: Vault Core
  • Type: Container
  • Description: The core logic of Vault.
  • Responsibilities: Enforcing policies, managing leases, handling revocation, coordinating with secret engines, auth methods, audit devices, and the storage backend.
  • Security Controls: ACLs, Policy enforcement, Lease management, Revocation.

• Element:

  • Name: Secret Engines
  • Type: Container
  • Description: Pluggable components that manage different types of secrets.
  • Responsibilities: Generating, storing, and managing specific types of secrets (e.g., key-value pairs, database credentials, certificates).
  • Security Controls: Specific to each secret engine; generally involve encryption and access control.

• Element:

  • Name: Auth Methods
  • Type: Container
  • Description: Pluggable components that handle authentication.
  • Responsibilities: Authenticating users and applications using various methods (e.g., LDAP, AppRole, Kubernetes).
  • Security Controls: Specific to each auth method; generally involve secure credential handling and integration with identity providers.

• Element:

  • Name: Audit Devices
  • Type: Container
  • Description: Pluggable components that handle audit logging.
  • Responsibilities: Sending audit logs to various destinations (e.g., syslog, file, Splunk).
  • Security Controls: Secure transmission of audit logs.

• Element:

  • Name: Storage Backend
  • Type: Container
  • Description: The persistent storage for Vault's encrypted data.
  • Responsibilities: Storing and retrieving data.
  • Security Controls: Data replication, backup, and recovery (provided by the storage backend); encryption at rest (provided by Vault).

DEPLOYMENT

Possible Deployment Solutions:

1. Single Server: Simplest deployment, suitable for development and testing. Not recommended for production.
2. High Availability (HA) Cluster with Consul: Uses Consul for service discovery and storage. Common and recommended for production.
3. High Availability (HA) Cluster with Integrated Storage (Raft): Uses Vault's built-in Raft-based storage. Simplified deployment and management. Also suitable for production.
4. Kubernetes: Vault can be deployed on Kubernetes using the official Helm chart.

Chosen Solution (for detailed description): High Availability (HA) Cluster with Integrated Storage (Raft)

graph LR
    subgraph Data Center 1
        VaultServer1[("Vault Server 1\n(Active)")]
        RaftStorage1[("Raft Storage 1")]
        VaultServer1 --> RaftStorage1 : Raft
    end

    subgraph Data Center 2
        VaultServer2[("Vault Server 2\n(Standby)")]
        RaftStorage2[("Raft Storage 2")]
        VaultServer2 --> RaftStorage2 : Raft
    end

    subgraph Data Center 3
        VaultServer3[("Vault Server 3\n(Standby)")]
        RaftStorage3[("Raft Storage 3")]
        VaultServer3 --> RaftStorage3 : Raft
    end
    
    LoadBalancer[("Load Balancer")]
    
    Developers --> LoadBalancer
    Operators --> LoadBalancer
    Applications --> LoadBalancer
    LoadBalancer --> VaultServer1
    LoadBalancer --> VaultServer2
    LoadBalancer --> VaultServer3
    VaultServer1 -.-> VaultServer2 : Raft Replication
    VaultServer1 -.-> VaultServer3 : Raft Replication
    VaultServer2 -.-> VaultServer3 : Raft Replication

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Element Descriptions:

• Element:

  • Name: Vault Server 1 (Active)
  • Type: Node
  • Description: An instance of the Vault server, currently serving requests.
  • Responsibilities: Handling client requests, managing secrets, enforcing policies.
  • Security Controls: All Vault security controls (ACLs, encryption, etc.).

• Element:

  • Name: Raft Storage 1
  • Type: Node
  • Description: The Raft storage node associated with Vault Server 1.
  • Responsibilities: Persistently storing Vault data, participating in Raft consensus.
  • Security Controls: Data replication, encryption at rest (provided by Vault).

• Element:

  • Name: Vault Server 2 (Standby)
  • Type: Node
  • Description: A standby instance of the Vault server, ready to take over if the active server fails.
  • Responsibilities: Replicating data from the active server, monitoring the active server's health.
  • Security Controls: All Vault security controls.

• Element:

  • Name: Raft Storage 2
  • Type: Node
  • Description: The Raft storage node associated with Vault Server 2.
  • Responsibilities: Persistently storing Vault data, participating in Raft consensus.
  • Security Controls: Data replication, encryption at rest (provided by Vault).

• Element:

  • Name: Vault Server 3 (Standby)
  • Type: Node
  • Description: Another standby instance of the Vault server.
  • Responsibilities: Replicating data from the active server, monitoring the active server's health.
  • Security Controls: All Vault security controls.

• Element:

  • Name: Raft Storage 3
  • Type: Node
  • Description: The Raft storage node associated with Vault Server 3.
  • Responsibilities: Persistently storing Vault data, participating in Raft consensus.
  • Security Controls: Data replication, encryption at rest (provided by Vault).

• Element:

  • Name: Load Balancer
  • Type: Node
  • Description: Distributes traffic across available Vault servers.
  • Responsibilities: Directing client requests to the active Vault server, performing health checks.
  • Security Controls: TLS termination, DDoS protection.

BUILD

Vault's build process is complex and involves multiple steps and tools. The following is a simplified overview, focusing on security-relevant aspects.

graph LR
    Developer[("Developer")]
    GitHubRepo[("GitHub Repository\n(hashicorp/vault)")]
    CI[("CI/CD Pipeline\n(GitHub Actions)")]
    GoBuild[("Go Build")]
    Tests[("Tests\n(Unit, Integration, Acceptance)")]
    Linters[("Linters\n(gofmt, go vet, etc.)")]
    SAST[("SAST\n(CodeQL)")]
    Artifacts[("Build Artifacts\n(Binaries, Docker Images)")]
    DockerRegistry[("Docker Registry")]

    Developer --> GitHubRepo : Push code
    GitHubRepo --> CI : Trigger build
    CI --> GoBuild : Build Vault
    GoBuild --> Tests : Run tests
    GoBuild --> Linters : Run linters
    GoBuild --> SAST: Static Analysis
    Tests -- success --> GoBuild
    Linters -- success --> GoBuild
    SAST -- success --> GoBuild
    GoBuild --> Artifacts : Create artifacts
    Artifacts --> DockerRegistry: Publish Docker Image

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Build Process Description:

1. Developers push code changes to the GitHub repository.
2. GitHub Actions (CI/CD pipeline) is triggered.
3. The pipeline performs the following steps:
   • Checks out the code.
   • Sets up the Go environment.
   • Runs linters (e.g., gofmt, go vet) to enforce code style and identify potential issues.
   • Runs unit, integration, and acceptance tests.
   • Performs static analysis security testing (SAST) using tools like CodeQL to identify vulnerabilities.
   • Builds Vault binaries for various platforms.
   • Creates Docker images.
   • Publishes the Docker images to a Docker registry.
   • Potentially signs the binaries and images.

Security Controls in Build Process:

• Automated Build: The entire build process is automated, reducing the risk of manual errors and ensuring consistency.
• Linters: Enforce code style and identify potential issues early in the development lifecycle.
• Testing: Comprehensive testing (unit, integration, acceptance) helps ensure the quality and security of the code.
• SAST: Static analysis security testing helps identify vulnerabilities before they are deployed.
• Dependency Management: Go modules are used for dependency management, and dependencies are likely scanned for known vulnerabilities.
• Signed Artifacts: Binaries and Docker images may be signed to ensure their integrity and authenticity.
• Reproducible Builds: Efforts are likely made to ensure reproducible builds, allowing independent verification of the build process.

RISK ASSESSMENT

Critical Business Processes:

• Secret Management: The core process of storing, managing, and accessing secrets.
• Application Functionality: Applications rely on Vault to retrieve secrets; disruption to Vault can impact application availability and functionality.
• Infrastructure Security: Vault protects the credentials used to access critical infrastructure, making it a high-value target.
• Compliance: Vault helps organizations meet compliance requirements related to data protection.

Data Sensitivity:

• Secrets (API keys, passwords, certificates, encryption keys): Highly sensitive. Exposure could lead to unauthorized access to systems and data.
• Audit Logs: Contain sensitive information about secret access and management activities. Exposure could reveal access patterns and potential vulnerabilities.
• Vault Configuration: Contains sensitive information about the Vault deployment, including storage backend configuration and security policies. Exposure could aid attackers in compromising Vault.
• Data stored within secrets: Depending on usage, data stored within secrets can be of any sensitivity level.

QUESTIONS & ASSUMPTIONS

Questions:

• What specific compliance regulations are most relevant to the organization using Vault (e.g., GDPR, HIPAA, PCI DSS)? This will influence the configuration and auditing requirements.
• What is the expected scale of the Vault deployment (number of secrets, requests per second, number of users/applications)? This will impact the choice of storage backend and high availability configuration.
• What are the existing security tools and processes in place (e.g., SIEM, IDPS, vulnerability scanners)? This will determine how Vault integrates with the existing security infrastructure.
• What is the organization's risk tolerance? This will influence the level of security controls implemented.
• What level of detail is required for the threat model? This will determine the scope and depth of the threat modeling exercise.
• Are there any specific threat actors or attack scenarios that are of particular concern?
• What are the specific requirements for disaster recovery and business continuity?

Assumptions:

• BUSINESS POSTURE: The organization prioritizes security and understands the critical role of Vault in protecting sensitive data.
• BUSINESS POSTURE: The organization has a mature security program and is committed to following security best practices.
• SECURITY POSTURE: Vault will be deployed in a secure environment with appropriate network segmentation and access controls.
• SECURITY POSTURE: The organization will regularly review and update Vault's configuration and policies.
• SECURITY POSTURE: The organization will monitor Vault's audit logs and respond to any suspicious activity.
• DESIGN: Vault will be deployed in a high-availability configuration to ensure resilience.
• DESIGN: The chosen storage backend will be appropriately secured and managed.
• DESIGN: The build process will be secured and regularly reviewed for vulnerabilities.
• DESIGN: Developers and operators will be trained on how to use Vault securely.