Multiple vulnerabilities in Moxa devices


Multiple Vulnerabilities in Moxa devices


see "Vulnerable / tested versions"

Vulnerable Version

see "Vulnerable / tested versions"

Fixed Version

see "Solution"

CVE Number

CVE-2021-39278, CVE-2021-39279






Thomas Weber (Office Vienna) | SEC Consult Vulnerability Lab

Multiple devices, which are developed by MOXA Inc., are prone to different vulnerabilities, like authenticated command injection and a reflected cross-site scripting in the config-upload. Furthermore, outdated software was identified and one vulnerability was tested with a public exploit (CVE-2015-0235). All findings were verified by emulating the device with the MEDUSA scalable firmware runtime.

Vendor description

"Together, We Create Change. Moxa is committed to making a positive impact around the world. We put our all behind this commitment--from our employees, to our products and supply chain. In our local communities, we nurture and support the spirit of volunteering. We encourage our employees to contribute to community development, with an emphasis on ecology, education, and health. In our products, we invest in social awareness programs and environment-friendly policies at every stage of the product lifecycle. We make sure our manufacturing meets the highest standards with regards to quality, ethics, and sustainability."


Business recommendation

SEC Consult recommends to immediately apply the available patches from the vendor. A thorough security review should be performed by security professionals to identify further potential security issues.


Vulnerability overview/description

1) Authenticated Command Injection (CVE-2021-39279)

An authenticated command injection vulnerability can be triggered by issuing a GET request to the "/forms/web_importTFTP" CGI program which is available on the web interface. An attacker can abuse this vulnerability to compromise the operating system of the device. This issue was found by emulating the firmware of the device.

2) Reflected Cross-Site Scripting via Manipulated Config-File (CVE-2021-39278)

Via a crafted config-file, a reflected cross-site scripting vulnerability can be exploited in the context of the victim's browser. This config-file can be uploaded to the device via the "Config Import Export" tab in the main menu.

3) Known GNU glibc Vulnerabilities (CVE-2015-0235)

The used GNU glibc in version 2.9 is outdated and contains multiple known vulnerabilities. One of the discovered vulnerabilities (CVE-2015-0235, gethostbyname "GHOST" buffer overflow) was verified by using the MEDUSA scalable firmware runtime.

4) Multiple Outdated Software Components

Multiple outdated software components containing vulnerabilities were found by the IoT Inspector. The vulnerabilities 1), 2) and 3) were manually verified on an emulated device by using the MEDUSA scalable firmware runtime.

Proof of concept

1) Authenticated Command Injection (CVE-2021-39279)

The vulnerability can be triggered by navigating in the web interface to the tab:

"Main Menu"->"Maintenance"->"Config Import Export"

The "TFTP Import" menu is prone to command injection via all parameters. To exploit the vulnerability, an IP address, a configuration path and a filename must be set. If the filename is used to trigger the exploit, the payload in the interceptor proxy would be:

 2) Reflected Cross-Site Scripting via Manipulated Config-File (CVE-2021-39278)

The vulnerability can be triggered by navigating in the web interface to the tab:

"Main Menu"->"Maintenance"->"Config Import Export"

The "Config Import" menu is prone to reflected cross-site scripting via the upload of config files. Example of malicious config file:


Uploading such a crafted file triggers cross-site scripting as the erroneous value is displayed without filtering characters.

3) Known GNU glibc Vulnerabilities (CVE-2015-0235)

GNU glibc version 2.9 contains multiple CVEs like:
CVE-2016-1234, CVE-2015-7547, CVE-2013-7423, CVE-2013-1914, and more. The gethostbyname buffer overflow vulnerability (GHOST) was checked with the help of the exploit code from It was compiled and executed on the emulated device to test the system.

4) Multiple Outdated Software Components

The IoT Inspector recognized multiple outdated software components with known vulnerabilities:

BusyBox 1.18.5 06/2011
Dropbear SSH 2011.54 11/2011
GNU glibc 2.9 02/2009
Linux Kernel 2.6.27 10/2008
OpenSSL 0.9.7g 04/2005
Only found in the program "iw_director"
OpenSSL 1.0.0 03/2010

Vulnerable / tested versions

The following firmware versions for various devices have been identified to be vulnerable:

  • WAC-2004 / 1.7
  • WAC-1001 / 2.1
  • WAC-1001-T / 2.1
  • OnCell G3470A-LTE-EU / 1.7
  • OnCell G3470A-LTE-EU-T / 1.7
  • TAP-323-EU-CT-T / 1.3
  • TAP-323-US-CT-T / 1.3
  • TAP-323-JP-CT-T / 1.3
  • WDR-3124A-EU / 2.3
  • WDR-3124A-EU-T / 2.3
  • WDR-3124A-US / 2.3
  • WDR-3124A-US-T / 2.3

Vendor contact timeline

2020-10-09 Contacting vendor through
2020-10-12 Contact sends PGP key for encrypted communication and asks for the detailed advisory. Sent encrypted advisory to vendor.
2020-11-06 Status update from vendor regarding technical analysis. Vendor requested more time for fixing the vulnerabilities as more products are affected.
2020-11-09 Granted more time for fixing to vendor.
2020-11-10 Vendor asked for next steps regarding the advisory publication.
2020-11-11 Asked vendor for an estimation when a public disclosure is possible.
2020-11-16 Vendor responded that the product team can give a rough feedback.
2020-11-25 Asked for a status update.
2020-11-25 Vendor responded that the investigation is not done yet.
2020-12-14 Vendor provided a list of potential affected devices and stated that full investigation may take until January 2021 due to the list of CVEs that were provided with the appended IoT Inspector report. The patches may be available until June 2021.
2020-12-15 Shifted next status update round with vendor on May 2021.
2020-12-23 Vendor provided full list of affected devices.
2021-02-05 Vendor sieved out the found issues from 4) manually and provided a full list of confirmed vulnerabilities. WAC-2004 phased-out in 2019.
2021-02-21 Confirmed receive of vulnerabilities, next status update in May 2021.
2021-06-10 Asking for an update.
2021-06-15 Vendor stated, that the update will be provided in the next days.
2021-06-21 Vendor will give an update in the next week as Covid gets worse in Taiwan.
2021-06-23 Vendor stated, that patches are under development. Vendor needs more time to finish the patches.
2021-06-24 Set release date to 2021-09-01.
2021-07-02 Vendor provides status updates.
2021-08-16 Vendor provides status updates.
2021-08-17 Vendor asks for CVE IDs and stated, that WDR-3124A has phased-out.
2021-08-20 Sent assigned CVE-IDs to vendor. Asked for fixed version numbers.
2021-08-31 Vendor provides fixed firmware version numbers and the advisory links.
2021-09-01 Coordinated release of security advisory.


According to the vendor the following patches must be applied to fix issues:

  • WAC-1001 / 2.1.5
  • WAC-1001-T / 2.1.5
  • OnCell G3470A-LTE-EU / 1.7.4
  • OnCell G3470A-LTE-EU-T / 1.7.4
  • TAP-323-EU-CT-T / 1.8.1
  • TAP-323-US-CT-T / 1.8.1
  • TAP-323-JP-CT-T / 1.8.1

The Moxa Technical Support must be contacted for requesting the security patches. The corresponding security advisories for the affected devices are available on the vendor's website:


OnCell G3470A-LTE/WDR-3124A

The following device models are EOL and should be replaced:

  • WAC-2004
  • WDR-3124A-EU
  • WDR-3124A-EU-T
  • WDR-3124A-US
  • WDR-3124A-US-T




EOF Thomas Weber / @2021

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