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Dstack Security Audit

Phala Network engaged zkSecurity to conduct a comprehensive security audit of the dstack project in May 2025. This audit provides an independent assessment of dstack’s security architecture, implementation quality, and production readiness.

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Audit Overview

Auditor: zkSecurity Engagement Period: May 26 - June 13, 2025 Audit Team: Two security consultants Report Date: May 26, 2025

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Scope

The audit covered two primary areas:

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Low-Level Libraries and Tooling

  • ra-tls and ra-rpc: Remote attestation TLS implementation
  • guest-agent: In-CVM service for key derivation and attestation
  • dstack-util: CLI tools including full-disk encryption functionality
  • Yocto BitBake recipes: Production image build configurations
  • Base initialization scripts: System setup and hardening
  • Production vs development images: Security difference analysis

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Methodology

The audit followed a two-phase approach: Phase 1: Core Security Analysis
  • Understanding attacker models and trust boundaries
  • Reviewing RATLS (Remote Attestation TLS) protocol implementation
  • Analyzing CVM interfaces and access controls
  • Evaluating privilege escalation strategies
Phase 2: System Image Analysis
  • Reviewing build reproducibility
  • Validating measurement integrity
  • Analyzing production image hardening
  • Assessing dm-verity integration
  • Evaluating host operator attack vectors

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Key Findings Summary

The audit identified 12 findings across different risk levels:
Risk LevelCountExamples
High1VMM currently trusted in OVMF build
Medium6Terminal binaries in production, symbolic link vulnerabilities
Low3Incomplete measurement checks, documentation gaps
Informational2Production deployment guidance, design documentation

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Critical Finding: OVMF Configuration

The highest-severity finding identified that dstack was using OVMF Configuration A, which trusts the Virtual Machine Manager (VMM). The audit recommended moving to Configuration B, which places the VMM outside the Trusted Computing Base (TCB). Impact: This configuration choice affects the fundamental trust model of the TEE environment. Status: ✅ Addressed - Dstack team implemented the recommended OVMF Configuration B.

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Implementation Status

The dstack team has been proactive in addressing audit findings: ✅ Fixed: OVMF configuration upgraded to secure mode ✅ Fixed: Production image hardening improvements ✅ Fixed: Symbolic link vulnerability patched ✅ Fixed: Terminal binary removal from production ✅ Enhanced: Documentation and security guides added

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Access Full Report

Download Complete Audit Report

Access the complete 39-page security audit report with detailed technical findings, recommendations, and implementation guidance.

Dstack Overview

Learn about dstack’s architecture and core concepts

Security Architecture

Understand Phala Cloud’s security model

Attestation Guide

Deep dive into TEE attestation mechanisms

Production Checklist

Security checklist for production deployments