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Advisory (ICSA-16-042-01A)

Moxa EDR-G903 Secure Router Vulnerabilities (Update A)

Original release date: May 17, 2016 | Last revised: December 22, 2016

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This updated advisory is a follow-up to the original advisory titled ICSA-16-042-01 Moxa EDR‑G903 Secure Router Vulnerabilities that was published May 17, 2016, on the NCCIC/ICS-CERT web site.

Independent researcher Maxim Rupp has identified vulnerabilities in Moxa’s EDR‑G903 secure routers. Moxa has produced a new firmware version to mitigate these vulnerabilities.

These vulnerabilities could be exploited remotely.


The following Moxa Secure Routers are affected:

  • EDR-G903 Versions V3.4.11 and older.


Successful exploitation of these vulnerabilities may allow a remote attacker to escalate privileges, initiate a denial-of-service condition, and execute arbitrary code.

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 product, Moxa EDR-G903 series, is an industrial virtual private network (VPN) server with firewall/NAT all-in-one secure router. It is designed for Ethernet security applications in sensitive remote control or monitoring networks, According to Moxa, these secure routers are deployed across several sectors, including, Commercial Facilities, Critical Manufacturing, Emergency Services, Energy, and others. Moxa estimates that these products are used globally but concentrated in the US, Europe, Chile, Argentina, Peru, Columbia, and Taiwan; 50 to 60 percent of all sales are in the US.




By accessing a specific uniform resource locator (URL) on the web server, a malicious user is able to access configuration and log files.

CVE-2016-0875b has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).c


Configuration files contain passwords in plaintext.

CVE-2016-0876e has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).f

--------- Begin Update A Part 1 of 2 --------


Ping function is available to every user, which may cause a memory leak in the affected device.

CVE-2016-0877h has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H).i

--------- End Update A Part 1 of 2 ----------


By sending malicious requests in the form of a ping twice, the device independently produces “Cold start.”

CVE-2016-0878k has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).l

--------- Begin Update A Part 2 of 2 --------


After using the import function of configuration or log files they are not deleted from server side, and any attacker is able to download them “without authenticating” by accessing a specific URL.

CVE-2016-0879n has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).o

--------- End Update A Part 2 of 2 ----------



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 created firmware version v3.4.12, and it is available to users upon request.


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 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.

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.

Contact Information

For any questions related to this report, please contact the NCCIC at:

Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  http://ics-cert.us-cert.gov 
or incident reporting:  https://ics-cert.us-cert.gov/Report-Incident?

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