There are new vulnerabilities discovered every day, and new patches issued to fix them. As part of our mission to secure the world’s OT, IoT and Cyber Physical infrastructures, we invest resources into offensive research of vulnerabilities and attack techniques. 

SCADAfence’s security researcher Yossi Reuven discovered a new vulnerability in the CODESYS development system. CVE-2021-30186 is a CVSS 8.8 (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) vulnerability which is a crafted request that may cause a heap-based buffer overflow in the affected CODESYS products, resulting in a denial-of-service condition.

CODESYS is a development environment for programming controller applications according to the international industrial standard IEC 61131-3. The main product of the software suite is the CODESYS Development System, an IEC 61131-3 tool. 

About the Vulnerability- CVE-2021-30186 

V2 runtime systems are one of the main products offered by CODESYS which provides SDK for the implementation of industrial IEC 61131-3 controllers with a customized PLC runtime system. 

The CODESYS Control runtime system enables embedded or PC-based devices to be a programmable industrial controller. It provides a communication server for communication with clients like the CODESYS Development System. A single crafted request may cause a heap-based buffer overflow in the affected CODESYS products, resulting in a denial-of-service condition. This simple but severe vulnerability can be exploited remotely. 

What SCADAfence Recommends Customers Do

Perform an Industrial Vulnerability Management Process

Please refer to our guide on this topic:

Monitor for Unauthorized Network Activity and Exploitation

Some devices will always remain unpatched. Monitoring is an early warning system that allows you to act before attackers have gained full control over your network.

Upgrade to the Latest Firmware

CODESYS is currently working on patches that will fix the following versions of the affected products:

  • CODESYS Runtime Toolkit 32 bit full prior version V2.4.7.55
  • CODESYS PLCWinNT prior version V2.4.7.55. This will also be part of the CODESYS Development System setup version V2.3.9.66.

CODESYS expects the releases of all the versions to be available in early May 2021. When the patch is available, we recommend asset owners consider upgrading the products.

Prevent Unauthorized and Untrusted Access

We recommend that CODESYS customers use controllers and devices only in a protected environment to minimize network exposure and ensure that they are not accessible from outside. Additionally, we recommend adopting a Firewall or VPN (Virtual Private Networks) tunnel to protect and separate the control system network from unauthorized access from other networks and unsecured remote access. 

Special Thanks & Recognition

The SCADAfence Research team would like to thank the CODESYS team for the collaboration and a speedy vulnerability reporting process.

CODESYS has published the advisory (2021-06) and released a firmware update to part of the product line.

SCADAfence is committed to continued research of offensive technologies and the development of new defensive technologies.

If you want to try out the SCADAfence Platform and uncover all of the vulnerabilities in your OT network, we will be glad to help you. Book your free demo here: