How to remediate – Treck/Kasago Network Stack Detection With IP Option.

1. Introduction

The Treck/Kasago Network Stack Detection With IP Option vulnerability identifies attempts to detect the Treck or Kasago TCP/IP stack on a system. This is important because these stacks contain Ripple20 vulnerabilities, which could allow for remote code execution. Systems commonly affected are embedded devices and industrial control systems using the Treck or Kasago network stack. A successful exploit could compromise confidentiality, integrity, and availability of the host.

2. Technical Explanation

This vulnerability involves sending malformed packets to a remote host to identify if it’s running the vulnerable Treck or Kasago TCP/IP stack (CVE-2020-11909). An attacker could use this information to target systems for further exploitation of Ripple20 vulnerabilities. The plugin does not exploit the vulnerability itself, but detects its presence.

• Root cause: The Treck and Kasago TCP/IP stacks improperly handle IP options in packets.
• Exploit mechanism: An attacker sends specially crafted packets with unusual IP options to a target host. A specific response from the host indicates the presence of the vulnerable stack.
• Scope: Systems running the Treck or Kasago TCP/IP stack are affected, particularly those not patched against Ripple20 (CVE-2020-11909).

3. Detection and Assessment

Confirming a system is vulnerable involves checking for responses to malformed packets. A quick check can be done by examining network traffic patterns, while thorough assessment uses vulnerability scanners.

• Quick checks: Network monitoring tools may show unusual TCP/IP behaviour when the scanner sends test packets.
• Scanning: Nessus plugin ID 139748 detects the Treck/Kasago stack. This is an example only, and results should be verified.
• Logs and evidence: Examine network logs for responses to malformed IP packets sent from the scanning host.

tcpdump -i eth0 'ip[2:2] - ((ip[0]&0xf)<<2)'

4. Solution / Remediation Steps

Fixing this issue requires patching or updating systems running the vulnerable stack. These steps should be performed carefully to avoid service disruption.

4.1 Preparation

• Ensure you have access to the latest patches or firmware updates from Treck or your device vendor. A roll back plan is to restore from the pre-patch backup.
• Change windows may be needed for critical systems; approval should come from IT management.

4.2 Implementation

1. Step 1: Download the latest patch or firmware update from Treck's website (https://www.treck.com/).
2. Step 2: Install the downloaded patch or apply the firmware update according to the vendor’s instructions.
3. Step 3: Reboot the system if required by the patching process.

4.3 Config or Code Example

Before

// No specific configuration example available as this is a TCP/IP stack vulnerability.  Focus on updating firmware versions.

After

// Verify updated firmware version after patching. Example: Firmware Version 2.5.1 (or newer) installed.

4.4 Security Practices Relevant to This Vulnerability

Practices that directly address this vulnerability include a robust patch management process and network segmentation. Least privilege can reduce impact if exploited.

• Practice 1: Implement a regular patch cadence for all systems, especially embedded devices.
• Practice 2: Segment networks to isolate vulnerable systems from critical assets.

4.5 Automation (Optional)

# Example PowerShell script to check firmware version (adapt for your system)
# This is an example only; adjust paths and commands as needed.
$firmwareVersion = Get-WmiObject -Class Win32_OperatingSystem | Select-Object Version
if ($firmwareVersion -lt "2.5.1") {
    Write-Host "Vulnerable firmware detected. Update required."
} else {
    Write-Host "Firmware is up to date."
}

5. Verification / Validation

Confirm the fix by re-running the vulnerability scan and verifying that no longer detects the vulnerable stack. Perform a service smoke test to ensure functionality remains intact.

• Post-fix check: Run `tcpdump -i eth0 'ip[2:2] - ((ip[0]&0xf)<<2)'` and confirm no unusual responses are seen when traffic is generated.
• Re-test: Re-run the Nessus scan (plugin ID 139748) and verify it does not report the Treck/Kasago stack.
• Smoke test: Verify basic network connectivity, such as pinging external websites or accessing shared resources.
• Monitoring: Monitor network logs for any unexpected traffic patterns related to IP options.

tcpdump -i eth0 'ip[2:2] - ((ip[0]&0xf)<<2)' # Should show no responses after patching

6. Preventive Measures and Monitoring

Update security baselines to include minimum firmware versions for affected devices. Implement checks in CI/CD pipelines to prevent deployment of vulnerable systems.

• Baselines: Update your security baseline or policy to require a minimum Treck/Kasago stack version that is patched against Ripple20.
• Pipelines: Add static analysis tools (SAST) and software composition analysis (SCA) to detect vulnerable components in build processes.
• Asset and patch process: Review system configurations regularly, at least quarterly, to ensure they meet security standards.

7. Risks, Side Effects, and Roll Back

Patching may cause temporary service disruption or compatibility issues with other systems. A roll back plan involves restoring from the pre-patch backup.

• Risk or side effect 1: Patching could temporarily interrupt network connectivity. Mitigate by scheduling during a maintenance window.
• Risk or side effect 2: Firmware updates may cause compatibility issues with existing hardware. Test in a non-production environment first.

8. References and Resources

• Vendor advisory or bulletin: https://www.treck.com/
• NVD or CVE entry: https://nvd.nist.gov/vuln/detail/CVE-2020-11909
• Product or platform documentation relevant to the fix: Refer to Treck's official documentation for specific patching instructions.