ICS Advisory

Moxa OnCell Vulnerabilities (Update A)

Last Revised
Alert Code


This updated advisory is a follow-up to the original advisory titled ICSA-16-236-01 Moxa OnCell Vulnerabilities that was published August 23, 2016, on the NCCIC/ICS-CERT web site.

Independent researcher Maxim Rupp has identified several vulnerabilities in Moxa’s OnCell products. Moxa has produced new firmware to mitigate these vulnerabilities.

These vulnerabilities could be exploited remotely.


Moxa reports that the vulnerability affects the following products:

  • OnCell G3100V2 Series, editions prior to Version 2.8, and
  • OnCell G3111/G3151/G3211/G3251 Series, editions prior to Version 1.7


An attacker could exploit these vulnerabilities to bypass authentication to log in as a valid user.

Impact to individual organizations depends on many factors that are unique to each organization. ICS-CERT recommends that organizations evaluate the impact of these vulnerabilities based on their operational environment, architecture, and product implementation.


Moxa is a Taiwan-based company that maintains offices in several countries around the world, including the US, UK, India, Germany, France, China, Russia, and Brazil.

The affected products, OnCell 31XX and 32XX series devices, are cellular IP gateways that can connect serial or Ethernet devices to a cellular network. According to Moxa, OnCell IP gateways are deployed across several sectors including Commercial Facilities, Critical Manufacturing, Energy, and Transportation Systems. Moxa estimates that these products are used primarily in Asia and Europe.



IMPROPER RESTRICTION OF EXCESSIVE AUTHENTICATION ATTEMPTSCWE-307: Improper Restriction of Excessive Authentication Attempts, http://cwe.mitre.org/data/definitions/307.html, web site last accessed August 23, 2016.

An attacker can freely use brute force to determine parameters needed to bypass authentication.

CVE-2016-5799NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5799, web site last accessed August 30, 2016. 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).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, web site last accessed August 23, 2016.

PLAINTEXT STORAGE OF A PASSWORDCWE-256: Plaintext Storage of a Password, http://cwe.mitre.org/data/definitions/256.html, web site last accessed August 23, 2016.

A configuration file contains parameters that represent passwords in plaintext.

CVE-2016-5812NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5812, web site last accessed August 30, 2016. has been assigned to this vulnerability. A CVSS v3 base score of 3.3 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N, web site last accessed August 23, 2016.

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CROSS-SITE SCRIPTINGCWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), http://cwe.mitre.org/data/definitions/79.html, web site last accessed August 30, 2016.

The reflected cross-site scripting attack may allow an attacker to execute arbitrary script code in the user’s browser within the trust relationship between their browser and the server.

CVE-2016-5819NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5819 , NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N, web site last accessed August 30, 2016.

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These vulnerabilities could be exploited remotely.


No known public exploits specifically target these vulnerabilities.


An attacker with a low skill would be able to exploit these vulnerabilities.


Moxa has made firmware fixes available on their web site at the following locations:



Moxa offers the following advice for upgrading firmware:

The OnCell G3111/G3151-HSPA’s firmware can be upgraded though the web console, serial console, or through OnCell Search Utility. However, Moxa recommends a local (LAN) connection to the OnCell to minimize the risk of a broken connection during the upgrade process. If you have made any changes to your configuration, remember to save the configuration first before upgrading the firmware. Any unsaved changes will be discarded when the firmware is upgraded. To upgrade the firmware, simply browse to the location of the firmware on your PC, and select Submit.

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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.

ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

ICS-CERT also provides a section for control systems security recommended practices on the ICS-CERT web page at: http://ics-cert.us-cert.gov/content/recommended-practices. 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 in the ICS‑CERT Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies, that is available for download from the ICS-CERT web site (http://ics-cert.us-cert.gov/).

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

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