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Security Advisories

SUMMARY

CVE-2002-20001: Resource Exhaustion Vulnerability in Diffie-Hellman Key Exchange Protocol

  • Security Advisory ID: MPSA-258261
  • Version: V1.0
  • Release Date: Jun 02, 2025
  • Reference:

    CVE-2002-20001 (MITRE) 

A resource exhaustion vulnerability, CVE-2002-20001, exists in the implementation of the Diffie-Hellman key exchange protocol.  

The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary numbers that are actually not public keys and trigger expensive server-side DHE modular-exponentiation calculations, also known as a D(HE)at or D(HE)ater attack. The client needs very little CPU resources and network bandwidth. The attack may be more disruptive where a client can require a server to select its largest supported key size. The basic attack scenario requires the client to claim DHE-only communication capabilities, and the server must be configured to permit DHE. 

This vulnerability affects any product or service that accepts DHE cipher suites. To mitigate the risk, Moxa has released solutions for the affected products. We recommend applying the appropriate solutions immediately. 

The Identified Vulnerability Type and Potential Impact 

CVE ID Vulnerability Type Impact
CVE-2002-20001

CWE-400: Uncontrolled Resource Consumption 

An attacker can force the server to perform high-cost modular exponentiation operations. This leads to significant CPU usage on the server side, potentially degrading service availability or resulting in a complete denial of service. 

Vulnerability Scoring Details 

CVE ID
Base Score
Vector
Severity

Unauthenticated

Remote Exploits

CVE-2002-20001 

CVSS:3.1: 7.5 

AV:N/AC:L/PR:N/UI:N/S:U/ C:N/I:N/A:H 

High  Yes 
AFFECTED PRODUCTS AND SOLUTIONS

Products Affected by CVE-2002-20001

Affected products and their firmware versions are listed in the following table: 

Product Series Affected Versions
ICS-G7848A Series  Firmware version 5.10 and earlier 
ICS-G7850A Series  Firmware version 5.10 and earlier
ICS-G7852A Series  Firmware version 5.10 and earlier

 

Solutions

Moxa has developed appropriate solutions to address this vulnerability. The solutions for the affected products are listed in the following table: 

Product Series Solutions
ICS-G7848A Series  Please contact Moxa Technical Support for the security patch
ICS-G7850A Series  Please contact Moxa Technical Support for the security patch
ICS-G7852A Series  Please contact Moxa Technical Support for the security patch

 

Mitigations

To mitigate the risks associated with this vulnerability, we recommend the following actions:

  • Refer to the General Security Recommentations section to further strengthen your security posture.

 

General Security Recommendations

To safeguard devices and networks, we recommend implementing the following recommendations to mitigate potential risks:

  1. Restrict Network Access
    • Use firewalls or access control lists (ACLs) to limit communication to trusted IP addresses and networks.
    • Segregate operational networks from other networks (e.g., enterprise networks) using VLANs or physical separation.
  2. Minimize Exposure
    • Avoid exposing devices directly to the Internet.
    • Disable unused network services and ports to reduce the attack surface.
  3. Enhance Device Authentication and Access Control
    • Implement multi-factor authentication (MFA) for accessing critical systems.
    • Use role-based access control (RBAC) to enforce the principle of least privilege.
  4. Regularly Update Firmware and Software
    • Keep devices updated with the latest firmware versions and security patches.
    • Establish a regular patch management schedule to address newly identified vulnerabilities.
  5. Secure Remote Access
    • Use encrypted communication protocols (e.g., VPN, SSH) for remote access.
    • Restrict remote access to authorized personnel only and enforce strong authentication mechanisms.
  6. Implement Anomaly Detection Techniques
    • Monitor network traffic and device behavior for unusual or unauthorized activities.
    • Use tools or techniques that can identify anomalies and provide alerts for potential threats.
  7. Implement Logging and Monitoring
    • Enable event logging and maintain audit trails on devices.
    • Regularly review logs for anomalies and unauthorized access attempts.
  8. Conduct Regular Security Assessments
    • Perform vulnerability assessments to identify potential risks.
    • Regularly review device configurations to ensure compliance with security policies.

 

Revision History:

VERSION DESCRIPTION RELEASE DATE
1.0 First release June 2, 2025

Relevant Products

ICS-G7848A Series · ICS-G7850A Series · ICS-G7852A Series ·

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