attack-surface.md

Attack Surface Analysis for zerotier/zerotierone

Attack Surface: 1. Controller Compromise

• Description: An attacker gains unauthorized access to the ZeroTier network controller (either ZeroTier's hosted service or a self-hosted instance). This remains the most critical attack vector directly related to ZeroTier.
• ZeroTier One Contribution: ZeroTier's architecture fundamentally relies on centralized controllers for network management, membership, and rule enforcement. The controller is the central point of trust and control.
• Example: An attacker exploits a vulnerability in the controller's web interface or uses stolen administrator credentials to gain access.
• Impact:
  • Complete control over the virtual network.
  • Ability to eavesdrop on all network traffic (MITM).
  • Ability to inject malicious traffic.
  • Ability to add/remove devices and modify network rules (including bypassing security policies).
  • Potential for complete network shutdown.
• Risk Severity: Critical
• Mitigation Strategies:
  • Strong Authentication: Enforce strong, unique passwords and mandatory multi-factor authentication (MFA) for all controller access (both UI and API).
  • Regular Updates: Keep the controller software (if self-hosted) meticulously up-to-date with the latest security patches. Automated updates are strongly recommended.
  • Strict Access Control: Restrict controller API access to only the absolutely necessary IP addresses using firewall rules. Implement a "deny by default" policy.
  • Comprehensive Auditing: Regularly audit controller logs (authentication attempts, configuration changes, etc.) for any suspicious activity. Implement automated alerting for anomalies.
  • Self-Hosting Security (if applicable): If self-hosting, treat the controller server as a critical asset. Harden it with a robust firewall, intrusion detection/prevention systems (IDS/IPS), and regular, in-depth security audits. Consider a dedicated, isolated network segment.
  • Least Privilege: Grant only the absolutely necessary permissions to controller users and API keys. Avoid using "administrator" accounts for routine tasks.

Attack Surface: 2. Client Device Compromise (with identity.secret Theft)

• Description: An attacker gains control of a device running the ZeroTier One client and successfully obtains the identity.secret file. This is a direct attack on a core ZeroTier component.
• ZeroTier One Contribution: The identity.secret file is the fundamental cryptographic identity of a ZeroTier node. Its compromise allows for complete and undetectable impersonation of that node on the network.
• Example: Malware on a user's device steals the identity.secret file, allowing the attacker to join the ZeroTier network with the same privileges as the compromised user.
• Impact:
  • Full, authenticated access to the ZeroTier network as the compromised device.
  • Ability to eavesdrop on traffic, inject malicious traffic, and access all network resources accessible to the impersonated device.
  • Potential to use the compromised device as a pivot point to attack other devices on the network (lateral movement).
• Risk Severity: High
• Mitigation Strategies:
  • Robust Endpoint Security: Implement and maintain robust endpoint security measures (antivirus, EDR, host-based firewalls, application whitelisting) on all devices running the ZeroTier client.
  • Strict File System Permissions: Ensure that the identity.secret file has the strictest possible file system permissions, preventing unauthorized access by any user or process other than the ZeroTier client itself.
  • User Education: Educate users about the critical importance of protecting their devices and the dangers of phishing, malware, and social engineering.
  • Immediate Device Deauthorization: If a device is suspected of being compromised, immediately deauthorize it from the ZeroTier controller. This is a crucial incident response step.
  • Hardware Security Modules (HSMs): For high-security environments (e.g., critical infrastructure), strongly consider using HSMs to store the cryptographic keys. This makes key theft significantly more difficult, even with physical access to the device.
  • Regular Security Audits: Conduct regular security audits of devices and user accounts, including checks for unauthorized software and configuration changes.

Attack Surface: 3. ZeroTier One Client Vulnerability Exploitation

• Description: An attacker exploits a vulnerability in the ZeroTier One client software itself to gain unauthorized access or control. This is a direct attack on the ZeroTier software.
• ZeroTier One Contribution: The ZeroTier One client is a complex piece of software, and like all software, it may contain vulnerabilities.
• Example: A remotely exploitable buffer overflow vulnerability in the client's network packet handling code could allow an attacker to execute arbitrary code on the device.
• Impact:
  • Highly variable, depending on the specific vulnerability. Could range from denial of service to complete remote code execution (RCE) and full device compromise.
• Risk Severity: High (depending on the vulnerability; assume high until proven otherwise)
• Mitigation Strategies:
  • Mandatory Automatic Updates: Enforce automatic updates for the ZeroTier One client. Do not allow users to disable updates. This is the single most important mitigation.
  • Proactive Vulnerability Monitoring: Actively monitor security advisories and vulnerability databases (e.g., CVE) for ZeroTier-related issues. Have a process in place to rapidly assess and respond to new vulnerabilities.
  • Sandboxing (where feasible): If technically possible and practical, consider running the ZeroTier client in a sandboxed or containerized environment to limit the impact of potential exploits. This adds a layer of defense.
  • System Hardening: Apply general system hardening best practices to the device running the client. This reduces the overall attack surface and can mitigate some classes of vulnerabilities.