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Mitigation Strategies Analysis for home-assistant/core

Mitigation Strategy: Strict Integration Sandboxing (Core-Enforced)

  • Mitigation Strategy: Implement robust isolation between integrations and the core system, enforced by the core.

  • Description:

    1. Filesystem Isolation (Core): The core must enforce strict filesystem isolation. Each integration operates within a dedicated, restricted directory. The core prevents access outside this directory using technologies like chroot jails, containers (lightweight options like systemd-nspawn), or similar mechanisms.
    2. Network Isolation (Core): The core must control network access for integrations. A whitelist of allowed hosts/ports is enforced by the core, using network namespaces (Linux) or similar OS-level features. Integrations cannot bypass this.
    3. System Call Restriction (Core): The core must limit system calls. A seccomp profile (Linux) or equivalent is used to define a whitelist of allowed system calls for each integration. This is enforced at the kernel level.
    4. Process Isolation (Core): The core must run each integration as a separate process with limited privileges. The core prevents inter-process communication except through defined, secure channels managed by the core.
    5. Inter-Integration Communication Control (Core): The core must provide a secure, controlled mechanism (e.g., a message bus with access control) for inter-integration communication. Direct communication is prohibited.
    6. Resource Limits (Core): The core must enforce resource limits (CPU, memory, file descriptors) on integrations to prevent denial-of-service attacks or resource exhaustion.

  • Threats Mitigated:

    • Malicious Integrations (Critical): Prevents a compromised or malicious integration from gaining full control.
    • Vulnerable Integrations (High): Limits the impact of vulnerabilities; one compromised integration cannot compromise others or the core.
    • Privilege Escalation (Critical): Prevents integrations from escalating privileges.
    • Data Exfiltration (High): Limits the ability of a compromised integration to exfiltrate data.

  • Impact:

    • Malicious Integrations: Risk reduction: Very High.
    • Vulnerable Integrations: Risk reduction: High.
    • Privilege Escalation: Risk reduction: Very High.
    • Data Exfiltration: Risk reduction: High.

  • Currently Implemented:

    • Partial. Some process isolation and limited capabilities exist, but not full sandboxing with containers, strict network/filesystem control, or comprehensive seccomp profiles.

  • Missing Implementation:

    • Full filesystem isolation (chroot/containers).
    • Strict network isolation (network namespaces, whitelisting).
    • Comprehensive system call restriction (seccomp).
    • Controlled inter-integration communication.
    • Resource limits (CPU, memory).

Mitigation Strategy: Secure API Authentication and Authorization (Core Logic)

  • Mitigation Strategy: Implement strong authentication and authorization within the core API logic.

  • Description:

    1. Multi-Factor Authentication (MFA) Support (Core): The core must provide robust support for MFA (TOTP, U2F), making it easy to configure and strongly encouraging its use.
    2. Rate Limiting (Core): The core must implement rate limiting for login attempts and API requests to prevent brute-force attacks. This is handled within the core API logic.
    3. Secure Session Management (Core): The core must use secure session tokens (JWTs or similar) with appropriate expiration, secure flags (HttpOnly, Secure), and robust generation/validation logic.
    4. API Key/Token Management (Core): The core must provide a system for generating, managing, and revoking API keys/tokens, with granular permission control.
    5. Fine-Grained Authorization (Core): The core must implement a role-based access control (RBAC) system or similar, defining precisely which users/API clients can access which resources/actions. This is enforced within the core API handling.
    6. Input Validation and Sanitization (Core): The core must rigorously validate and sanitize all data received through the API (headers, parameters, bodies) before processing it. This is a core responsibility for all API endpoints.
    7. HTTPS Enforcement (Core): The core application must refuse any non-HTTPS connections for the API.

  • Threats Mitigated:

    • Unauthorized Access (Critical): Prevents unauthorized API access.
    • Brute-Force Attacks (High): Mitigates brute-force attempts.
    • Session Hijacking (High): Protects against session hijacking.
    • Privilege Escalation (Critical): Prevents unauthorized access to resources.
    • Injection Attacks (High): Prevents injection attacks via the API.
    • Man-in-the-Middle Attacks (High): HTTPS enforcement prevents MitM.

  • Impact:

    • Unauthorized Access: Risk reduction: Very High.
    • Brute-Force Attacks: Risk reduction: High.
    • Session Hijacking: Risk reduction: High.
    • Privilege Escalation: Risk reduction: Very High.
    • Injection Attacks: Risk reduction: High.
    • Man-in-the-Middle Attacks: Risk reduction: Very High.

  • Currently Implemented:

    • Mostly. HTTPS is used, password policies exist, long-lived access tokens are supported, MFA is available, and some authorization is in place.

  • Missing Implementation:

    • More comprehensive/easily configurable MFA.
    • More fine-grained authorization (formal RBAC).
    • Stricter, more consistent input validation/sanitization across all API endpoints.

Mitigation Strategy: Secure Configuration and Data Storage (Core Handling)

  • Mitigation Strategy: Protect sensitive data stored in configuration files, managed by the core.

  • Description:

    1. Encryption at Rest (Core): The core must encrypt sensitive data (passwords, API keys in secrets.yaml or similar) at rest using a strong algorithm (AES-256). The core handles the encryption/decryption process.
    2. Secure Key Management (Core Integration): The core should integrate with secure key management solutions (environment variables, external services like HashiCorp Vault) to store encryption keys separately from the configuration files. The core provides the mechanisms for this integration.
    3. Avoid Hardcoded Secrets (Core Development Practice): Core developers must never hardcode secrets.

  • Threats Mitigated:

    • Data Breach (Critical): Protects sensitive data if configuration files are compromised.
    • Unauthorized Access (Critical): Prevents unauthorized access to sensitive data.
    • Credential Theft (High): Makes credential theft more difficult.

  • Impact:

    • Data Breach: Risk reduction: Very High.
    • Unauthorized Access: Risk reduction: Very High.
    • Credential Theft: Risk reduction: High.

  • Currently Implemented:

    • Partially. secrets.yaml is used, but it's not natively encrypted by the core.

  • Missing Implementation:

    • Native encryption of secrets.yaml (or equivalent) by the core.
    • Built-in integration with secure key management solutions.

Mitigation Strategy: Secure Update Mechanism (Core Functionality)

  • Mitigation Strategy: Ensure the integrity and authenticity of updates, verified by the core.

  • Description:

    1. Code Signing Verification (Core): The core must verify the digital signature of any update before applying it. This verification logic is within the core update process.
    2. Rollback Mechanism (Core): The core must provide a mechanism to revert to a previous version if an update fails or causes issues. This is a core feature.
    3. Two-Factor Authentication for Release (Core Team Responsibility): Use 2FA for any accounts that have access to publish updates.

  • Threats Mitigated:

    • Malicious Updates (Critical): Prevents installation of malicious updates.
    • Tampering with Updates (High): Ensures updates haven't been tampered with.

  • Impact:

    • Malicious Updates: Risk reduction: Very High.
    • Tampering with Updates: Risk reduction: High.

  • Currently Implemented:

    • Mostly. Updates are signed and verified. A rollback mechanism likely exists.

  • Missing Implementation:

    • Potentially more robust key management (though this is more on the release process side).

Mitigation Strategy: Event Handling and Automation Security (Core Logic)

  • Mitigation Strategy: Secure the execution of automations and event handling within the core.

  • Description:

    1. Automation Sandboxing (Core): The core should consider sandboxing the execution of automations, similar to integrations, to limit their potential impact. This would involve restricting access to resources and system calls.
    2. Automation Validation (Core): The core must implement validation rules to prevent obviously dangerous automations (e.g., those that could unlock doors without authentication or perform other high-risk actions). This validation happens before the automation is saved or executed.
    3. Audit Logging (Core): The core must log all automation events, including triggers, conditions, and actions, for auditing and debugging purposes. This logging is a core feature.

  • Threats Mitigated:

    • Malicious Automations (Medium): Limits the damage a malicious automation can cause.
    • Accidental Misconfiguration (Medium): Prevents users from creating automations that could have unintended consequences.
    • Security Bypass (High): Prevents automations from bypassing security controls.

  • Impact:

    • Malicious Automations: Risk reduction: Medium to High.
    • Accidental Misconfiguration: Risk reduction: Medium.
    • Security Bypass: Risk reduction: High.

  • Currently Implemented:

    • Partially. Some validation and logging exist, but full automation sandboxing is not implemented.

  • Missing Implementation:

    • Automation sandboxing.
    • More comprehensive validation rules for automations.