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attack-surface.md

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Attack Surface Analysis for saltstack/salt

Attack Surface: 1. Compromised Salt Master

  • Description: An attacker gains full control of the Salt Master, allowing them to control all connected minions. This is the single most critical point of failure.
    • How Salt Contributes: The Salt Master is the central authority and communication hub. Its compromise grants complete control over the managed infrastructure.
    • Example: An attacker exploits a known vulnerability in the Salt Master service to gain root access to the Master server. They then use this access to deploy ransomware to all connected minions.
    • Impact: Complete system compromise. Loss of confidentiality, integrity, and availability of all managed systems. Potential for widespread data breaches and operational disruption.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Patching: Keep the Salt Master software up-to-date with the latest security patches. Prioritize patching known vulnerabilities.
      • Hardening: Harden the operating system of the Salt Master server. Disable unnecessary services and follow security best practices for the OS.
      • Network Segmentation: Isolate the Salt Master on a dedicated, secure network segment with strict firewall rules. Limit inbound access to only necessary ports (4505, 4506) and only from authorized minion IPs and administrative workstations.
      • Strong Authentication: Use strong, unique passwords for all Salt Master access (including API and CLI). Enforce multi-factor authentication (MFA) wherever possible.
      • Least Privilege: Configure Salt users and roles with the minimum necessary permissions. Avoid granting overly broad access.
      • TLS Encryption: Enforce TLS encryption for all Master-Minion communication. Verify minion keys diligently during the initial connection.
      • Auditing: Enable detailed logging on the Salt Master and regularly review logs for suspicious activity. Integrate with a SIEM system for centralized monitoring.
      • eAuth: If using external authentication, ensure the external provider is secure and the eAuth configuration is robust.
      • Regular Security Assessments: Conduct regular penetration testing and vulnerability scanning of the Salt Master and its host environment.

Attack Surface: 2. Rogue Minion Connection

  • Description: An unauthorized system connects to the Salt Master, potentially receiving configurations or executing commands intended for legitimate minions.
    • How Salt Contributes: Salt's architecture relies on minions connecting to the Master. If key management is weak, a rogue minion can impersonate a legitimate one.
    • Example: An attacker gains access to the network and configures a system to connect to the Salt Master, pretending to be a newly provisioned server. The attacker's system then receives sensitive configuration data.
    • Impact: Potential for data exfiltration, unauthorized command execution, and lateral movement within the network.
    • Risk Severity: High
    • Mitigation Strategies:
      • Strict Key Management: Implement a rigorous process for reviewing and approving minion key requests. Do not use auto_accept: True in production environments.
      • Manual Key Acceptance: Use auto_accept: False in the Master configuration to require manual approval of all minion keys.
      • Autosign Grains (Careful Use): If using autosign_grains, ensure the grains used for identification are truly unique and cannot be easily spoofed. Regularly audit the autosign_grains configuration.
      • Key Auditing: Regularly audit the list of accepted minion keys on the Salt Master. Remove any keys that are no longer needed or are suspicious.
      • Network Monitoring: Monitor network traffic for unauthorized connections to the Salt Master's ports.

Attack Surface: 3. Insecure State File Execution

  • Description: State files (.sls) containing vulnerabilities or misconfigurations are executed on minions, leading to security compromises.
    • How Salt Contributes: Salt states define the desired configuration of minions. Insecure states can introduce vulnerabilities.
    • Example: A state file contains hardcoded database credentials in plain text. An attacker who compromises a minion can read this file and gain access to the database.
    • Impact: Varies depending on the vulnerability. Could range from information disclosure to privilege escalation or remote code execution on the minion.
    • Risk Severity: High
    • Mitigation Strategies:
      • Pillar Data: Use Salt's pillar system to store sensitive data (passwords, API keys, etc.) outside of state files. Pillar data is encrypted and only accessible to specific minions.
      • Jinja Templating: Use Jinja templating to avoid hardcoding values and promote reusability and maintainability of state files.
      • Code Review: Implement a code review process for all state file changes. Ensure that security best practices are followed.
      • Least Privilege: Design states to grant only the minimum necessary permissions to files, users, and processes.
      • Version Control: Use a version control system (e.g., Git) to track changes to state files and facilitate rollbacks.
      • Static Analysis: Use a linter or static analysis tool to identify potential security issues in state files (e.g., insecure file permissions, hardcoded secrets).
      • Trusted Modules: Only use Salt modules from trusted sources. Carefully review any custom modules before deploying them.

Attack Surface: 4. Execution Module Abuse

  • Description: Attackers leverage Salt's execution modules (functions run on minions) to perform malicious actions.
    • How Salt Contributes: Salt provides powerful execution modules for managing systems. These modules can be misused if not properly controlled.
    • Example: An attacker with limited access to the Salt Master uses the cmd.run module to execute arbitrary shell commands on a target minion, escalating their privileges.
    • Impact: Potential for remote code execution, data exfiltration, privilege escalation, and denial of service on minions.
    • Risk Severity: High
    • Mitigation Strategies:
      • Module Blacklisting/Whitelisting: Use Salt's module_blacklist or module_whitelist configuration options to restrict the use of potentially dangerous modules (e.g., cmd.run, cmd.script). Prefer whitelisting to blacklisting for a more secure approach.
      • Least Privilege (Salt Users): Define Salt users and roles with the minimum necessary permissions to execute specific modules. Avoid granting broad access to all modules.
      • Auditing: Enable detailed logging of execution module usage and regularly review logs for suspicious activity.
      • Runners (for Privileged Tasks): Use Salt's runner modules (which run on the Master) for tasks that require elevated privileges, rather than running them directly on minions via execution modules. This centralizes privileged operations.
      • Input Validation: If custom execution modules are used, ensure they perform thorough input validation to prevent command injection or other vulnerabilities.

Attack Surface: 5. Salt API Vulnerability Exploitation

  • Description: An attacker exploits a vulnerability in the Salt API to gain unauthorized access to Salt functionality.
    • How Salt Contributes: The Salt API provides programmatic access to Salt. Vulnerabilities in the API can expose the entire system.
    • Example: An attacker discovers a cross-site scripting (XSS) vulnerability in the Salt API's web interface. They use this vulnerability to steal an administrator's session cookie and gain control of the Salt Master.
    • Impact: Similar to a compromised Salt Master – complete system compromise, data breaches, and operational disruption.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • API Patching: Keep the Salt Master software (which includes the API) up-to-date with the latest security patches.
      • Strong Authentication (API): Use strong, unique passwords and MFA for all Salt API access.
      • Access Control (API): Implement strict access controls to limit API access to authorized users and applications. Use Salt's client_acl configuration to define granular permissions.
      • Disable if Unused: If the Salt API is not needed, disable it entirely.
      • Reverse Proxy: If exposing the API, use a reverse proxy (e.g., Nginx, Apache) with proper security configurations (TLS, input validation, rate limiting, Web Application Firewall (WAF)).
      • Auditing (API): Enable detailed logging of Salt API usage and regularly review logs for suspicious activity.

Attack Surface: 6. Man-in-the-Middle (MitM) Attack on Master-Minion Communication

  • Description: An attacker intercepts and potentially modifies communication between the Salt Master and minions.
    • How Salt Contributes: Salt relies on network communication between the Master and minions. Without proper encryption, this communication is vulnerable to MitM attacks.
    • Example: An attacker uses ARP spoofing to redirect traffic between a minion and the Salt Master. They then intercept sensitive configuration data being sent to the minion.
    • Impact: Data interception, modification of commands and configurations, potential for impersonation of the Master or minions.
    • Risk Severity: High
    • Mitigation Strategies:
      • TLS Encryption (Mandatory): Enforce TLS encryption for all Master-Minion communication. This is the primary defense against MitM attacks. Ensure proper certificate validation is enabled.
      • Network Security: Implement strong network security measures, including network segmentation, intrusion detection and prevention systems (IDS/IPS), and regular network monitoring.
      • Secure Network Infrastructure: Use secure network devices and protocols. Avoid using unencrypted protocols (e.g., HTTP) for any Salt-related communication.