How to remediate – ALCASAR Detection

1. Introduction

ALCASAR Detection indicates that an open source network access controller is running on a remote host. ALCASAR manages network access and can affect systems relying on it for authentication and authorization. A successful compromise of the ALCASAR controller could lead to unauthorized network access, impacting confidentiality, integrity, and availability.

2. Technical Explanation

ALCASAR is an open source network access controller that provides RADIUS server functionality. The detection itself isn’t a vulnerability but flags a system running potentially unpatched software. Attackers could exploit vulnerabilities within ALCASAR to gain unauthorized access to the network. Preconditions include network connectivity to the ALCASAR instance and knowledge of its configuration.

• Root cause: Presence of an installed, potentially vulnerable, open source network access controller.
• Exploit mechanism: Attackers could exploit known vulnerabilities in ALCASAR through RADIUS protocol attacks or by compromising the server directly.
• Scope: Systems running ALCASAR on Linux platforms are affected.

3. Detection and Assessment

Confirming an ALCASAR installation can be done with a quick check of running processes, followed by more thorough inspection of configuration files.

• Quick checks: Use the command ps aux | grep alcasar to identify if the ALCASAR process is running.
• Scanning: Nessus or OpenVAS may have plugins for detecting ALCASAR; check their latest plugin sets.
• Logs and evidence: Check system logs (e.g., /var/log/syslog, /var/log/auth.log) for entries related to the alcasar service.

ps aux | grep alcasar

4. Solution / Remediation Steps

The primary solution is to ensure ALCASAR is patched with the latest security updates or, if no longer needed, remove it from the system.

4.1 Preparation

• Take a snapshot of the virtual machine or create a full system backup before making changes. Stop the alcasar service using systemctl stop alcasar.
• Ensure you have access to the latest ALCASAR packages and documentation. A roll back plan involves restoring from the backup if updates cause issues.
• A change window may be required depending on your organization’s policies. Approval from a system administrator is recommended.

4.2 Implementation

1. Step 1: Update the package repositories to ensure you have access to the latest versions using apt update or equivalent for your distribution.
2. Step 2: Upgrade ALCASAR with apt upgrade alcasar or equivalent.
3. Step 3: Restart the ALCASAR service using systemctl start alcasar.

4.3 Config or Code Example

This vulnerability does not involve a specific config change, but ensuring the latest package is installed is key.

Before

# Check ALCASAR version (example)
alcasar --version
Version: 0.1.2

After

# Check ALCASAR version (example)
alcasar --version
Version: 0.1.5  (or later)

4.4 Security Practices Relevant to This Vulnerability

Keeping software up-to-date is the most relevant practice for this vulnerability type.

• Practice 1: Patch cadence – Regularly update all software, including network infrastructure components like ALCASAR, to address known vulnerabilities.

4.5 Automation (Optional)

Automated patching can be achieved using configuration management tools such as Ansible or Puppet.

# Example Ansible task:
- name: Update alcasar package
  apt:
    name: alcasar
    state: latest

5. Verification / Validation

• Post-fix check: Run alcasar --version and confirm it displays a version equal to or later than the latest available.
• Re-test: Re-run ps aux | grep alcasar to ensure the service is running without errors.
• Smoke test: Test network access by attempting to connect with a valid user account through RADIUS authentication.
• Monitoring: Monitor system logs for any ALCASAR related errors or unusual activity.

alcasar --version

6. Preventive Measures and Monitoring

Regularly update security baselines to include the latest software versions, and incorporate vulnerability scanning into CI/CD pipelines.

• Baselines: Update your system baseline or hardening guide to require the latest ALCASAR version.
• Pipelines: Add a vulnerability scan step in your CI/CD pipeline that checks for known vulnerabilities in deployed packages like ALCASAR.
• Asset and patch process: Implement a regular patch review cycle (e.g., weekly) to identify and apply security updates for all systems.

7. Risks, Side Effects, and Roll Back

Updating ALCASAR could potentially disrupt network access if the update introduces compatibility issues.

• Risk or side effect 1: Network connectivity interruption during upgrade. Mitigation: Perform upgrades during a maintenance window with minimal user impact.
• Roll back: Restore from the pre-upgrade snapshot or backup if the update causes issues. Revert to the previous ALCASAR version using your package manager.

8. References and Resources

Refer to the official ALCASAR website for documentation and security advisories.

• Vendor advisory or bulletin: http://www.alcasar.net/