CVE-2025-30234

Remediation/Mitigation Strategy for CVE-2025-30234: SmartOS Static SSH Keys

This document outlines the remediation and mitigation strategy for CVE-2025-30234, a vulnerability affecting SmartOS, specifically within the 60f76fd2-143f-4f57-819b-1ae32684e81b image (a Debian 12 LX zone image from 2024-07-26).

1. Vulnerability Description

  • CVE ID: CVE-2025-30234
  • Description: The SmartOS image 60f76fd2-143f-4f57-819b-1ae32684e81b (Debian 12 LX zone image from 2024-07-26) contains static host SSH keys. This means that all instances created from this image share the same SSH host keys.
  • Affected System: SmartOS running the 60f76fd2-143f-4f57-819b-1ae32684e81b image (and potentially any derivatives of this image).

2. Severity

  • CVSS Score: 8.3 (High)
  • CVSS Vector: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L (This vector assumes network accessibility, low attack complexity, no privileges required, no user interaction, unchanged scope, high confidentiality impact, high integrity impact, and low availability impact)
  • Severity Justification: The use of static SSH host keys allows for potential “man-in-the-middle” attacks. An attacker who intercepts a connection to a SmartOS instance using this image can impersonate the server, potentially gaining access to sensitive information or executing arbitrary code. The high confidentiality and integrity impact drive the overall severity score. The Low availability impact is likely related to the effort needed to successfully execute a MITM attack versus readily compromising systems directly.

3. Known Exploit Information

  • While a specific exploit may not be publicly available (as of the date provided in the data), the nature of the vulnerability lends itself to standard “man-in-the-middle” techniques.
  • An attacker possessing the private SSH host key for the affected image can impersonate any server created from that image.
  • The risk is heightened because the image is publicly available, increasing the likelihood of attackers obtaining the static keys.

4. Remediation/Mitigation Strategy

The primary goal is to eliminate the use of static SSH host keys and ensure that each SmartOS instance has unique keys.

A. Immediate Mitigation (Short-Term):

  1. Identify Affected Instances: Inventory all SmartOS instances in your environment and determine which are running the vulnerable 60f76fd2-143f-4f57-819b-1ae32684e81b image (or derivatives).

  2. Rotate SSH Host Keys: For each affected instance, generate new SSH host keys. This will invalidate the shared, static keys. The command to generate new keys is:

    ssh-keygen -A

    This command will generate keys for all the standard SSH algorithms (rsa, dsa, ecdsa, ed25519). Alternatively, you can generate them individually:

    ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key

    ssh-keygen -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key ssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key Important: After regenerating the keys, restart the SSH service.

    systemctl restart sshd

    or

    service ssh restart

  3. Update Known Hosts: Clients connecting to the affected instances will receive a warning that the SSH host key has changed. Clients must verify the new SSH host key fingerprint before accepting it. Obtaining the correct fingerprint via out-of-band communication (e.g., phone call, secure messaging) is crucial to prevent MITM attacks.

    • Example of removing old entry from ~/.ssh/known_hosts:

          ssh-keygen -R hostname.example.com

      Replace hostname.example.com with the hostname or IP address of the affected instance.

B. Long-Term Remediation:

  1. Update Image Creation Process: The process for creating SmartOS images (especially LX zone images) must be modified to ensure that SSH host keys are not included in the base image. Instead, keys should be generated during the first boot sequence or via a configuration management system.

  2. Create a New Base Image: Create a new base image derived from Debian 12 (or your preferred base operating system) that does not contain any pre-generated SSH host keys. This new image will be the foundation for all future LX zone deployments.

  3. Automate Key Generation: Implement a mechanism to automatically generate SSH host keys on first boot of the LX zone. This can be accomplished through cloud-init, a custom script, or a configuration management system like Ansible, Chef, or Puppet.

    • Example (using cloud-init): You can add a runcmd section to your cloud-init configuration file to generate the keys:

          #cloud-config

      runcmd:

      • [ sh, -c, “ssh-keygen -A” ]
      • [ systemctl, restart, sshd ]
      1. Replace Existing Instances: Migrate existing instances running the vulnerable image to the new, secure image. This will require careful planning and execution to minimize downtime.

  4. Image Repository Security: Ensure the security of your image repository. Limit access to the repository and implement appropriate access controls to prevent unauthorized modification of images.

  5. Vulnerability Scanning: Implement a vulnerability scanning process to regularly scan SmartOS images and instances for known vulnerabilities, including missing security patches and insecure configurations.

C. Monitoring and Prevention:

  1. Monitor for Unauthorized SSH Key Changes: Implement monitoring to detect unexpected changes to SSH host keys. This can be accomplished through intrusion detection systems (IDS) or security information and event management (SIEM) systems.
  2. Implement SSH Hardening: Apply standard SSH hardening techniques, such as disabling password authentication, using key-based authentication only, and restricting SSH access to specific IP addresses or networks.
  3. Regularly Review and Update Images: Establish a process to regularly review and update SmartOS images to ensure they contain the latest security patches and are free from known vulnerabilities.

5. Communication

  • Inform all relevant stakeholders (e.g., system administrators, security team, application owners) about the vulnerability and the remediation steps being taken.
  • Provide clear instructions on how to verify the new SSH host keys and update their known_hosts file.

6. Validation

  • After implementing the remediation steps, verify that each affected instance has unique SSH host keys.
  • Test the connectivity to the instances to ensure that SSH access is working correctly.
  • Consider performing penetration testing to validate the effectiveness of the remediation efforts.

By implementing these remediation and mitigation steps, you can significantly reduce the risk associated with CVE-2025-30234 and improve the overall security of your SmartOS environment. Remember to tailor these recommendations to your specific environment and requirements.

Assigner

Date

  • Published Date: 2025-03-19 00:00:00
  • Updated Date: 2025-03-19 05:15:41

More Details

CVE-2025-30234