Tenant-Controlled Guest Agents for Secure Virtual Machine Configuration
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Solution Overview
Problem
In a cloud environment, virtual machine agents inherently trust commands from untrusted cloud service provider infrastructure, posing a security risk, especially in Confidential Computing scenarios where complete trust in the CSP is undesirable.
Innovation Solution
Implementing a guest agent as a trusted agent within the virtual machine, controlled by the tenant, which enforces policies through a policy enforcement agent to manage extension execution and communication securely, using a cryptographically secure channel to protect against malicious actors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If agents trust commands from CSP infrastructure components, then automation and management functionality are enabled, but security risks arise in Confidential Computing scenarios
Solution Approach 1:
The system segments the trust relationship by introducing a trusted agent component that operates independently from the traditional CSP-controlled agent. This trusted agent verifies and filters commands from CSP infrastructure, creating a separation between the automation functionality and the trust verification process. The trusted agent maintains local policy definitions that override CSP commands, enabling automation while preserving security control.
Solution Approach 2:
The trusted agent acts as an intermediary between CSP infrastructure components and the virtual machine environment. It receives commands from CSP components but verifies them against locally stored policy definitions before execution. This intermediary layer blocks malicious or unauthorized commands while allowing legitimate automation operations, resolving the contradiction between automation and security trust.
2Reliability
If agents and extensions are disabled to eliminate trust requirements, then security is improved, but VM management functionality is reduced
Solution Approach 1:
The trusted agent implements self-service by maintaining local policy definitions and autonomously verifying commands without requiring continuous CSP validation. It independently determines whether to execute or block commands based on its local policy store, eliminating the need for full CSP trust while preserving automation capabilities. This self-service approach enables security control without sacrificing management functionality.
Solution Approach 2:
The system performs preliminary action by pre-loading policy definitions into the trusted agent before it begins operation. These policy definitions establish the security rules and authorized operations in advance, allowing the trusted agent to autonomously make decisions about command execution. This preliminary configuration enables the agent to provide full management functionality while maintaining security without real-time CSP intervention.
3Reliability
If tenant-controlled policies are enforced to prevent unauthorized execution, then security is enhanced, but system complexity increases
Solution Approach 1:
The trusted agent merges multiple functions into a single component: it stores policy definitions, verifies commands from CSP infrastructure, filters extensions, and controls execution decisions. This consolidation reduces overall system complexity compared to having separate components for each function. The unified trusted agent manages tenant-controlled policies while maintaining compatibility with existing CSP infrastructure, achieving enhanced security without proportionally increasing complexity.
Data Source
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AI summary
A secure virtual machine configuration system comprises a host device implemented in a cloud service provider environment, a virtual machine implemented on the host, and a guest agent configured within the virtual machine. The guest agent includes a policy enforcement agent configured to monitor policies received therein from a tenant device over a secure communication channel between the tenant and the guest agent and to allow execution of software components that are specified within the policy enforcement agent.