ICS Advisory

Moxa NPort IAW5000A-I/O Series Serial Device Server

Last Revised
Alert Code
ICSA-21-187-01

1. EXECUTIVE SUMMARY

  • CVSS v3 9.8
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Moxa
  • Equipment: NPort IAW5000A-I/O Series Wireless Device Server
  • Vulnerabilities: Classic Buffer Overflow, Stack-based Buffer Overflow, Improper Input Validation, OS Command Injection

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could crash the device being accessed, cause a buffer overflow condition, or allow remote code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Moxa reports these vulnerabilities affect the following wireless device server:

  • NPort IAW5000A-I/O Series firmware Version 2.2 or earlier

3.2 VULNERABILITY OVERVIEW

3.2.1    CLASSIC BUFFER OVERFLOW CWE-120

Two buffer overflows in the built-in web server may allow a remote attacker to cause a denial-of-service condition.

CVE-2021-32968 has been assigned to these vulnerabilities. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.2    STACK-BASED BUFFER OVERFLOW CWE-121

Five buffer overflows in the built-in web server allow a remote attacker to initiate a denial-of-service attack and execute arbitrary code.

CVE-2021-32976 has been assigned to these vulnerabilities. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.2.3    IMPROPER INPUT VALIDATION CWE-20

Data can be copied without validation in the built-in web server, which may allow a remote attacker to cause denial-of-service conditions.

CVE-2021-32970 has been assigned to these vulnerabilities. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.4    OS COMMAND INJECTION CWE-78

Improper input validation in the built-in web server may allow a remote attacker to execute commands.

CVE-2021-32974 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Energy Sector
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Taiwan

3.4 RESEARCHER

Konstantin Kondratev, Evgeniy Druzhinin and Ilya Karpov of Rostelecom-Solar reported these vulnerabilities to Moxa.

4. MITIGATIONS

Moxa has developed solutions to address these vulnerabilities. Please contact Moxa Technical Support for a security patch.

Moxa has also published a security advisory to provide more information.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

  • Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
  • Locate control system networks and remote devices behind firewalls, and isolate them from the business network.
  • When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing that VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize that VPN is only as secure as the connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.cisa.gov. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage on us-cert.cisa.gov in the Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target these vulnerabilities.

This product is provided subject to this Notification and this Privacy & Use policy.

Vendor

Moxa