An authenticated attacker can send a malformed packet to trigger a device crash via the CODESYS V2 runtime commands parsing.

Abusing these vulnerabilities an attacker can crash an affected product, which fully prevents the product to work as intended. After a complete restart the component works as expected.

Mitigation

If the PLC runtime is running, but you do not need it, you can deactivate the plc runtime programming port over the product settings in the web-based management. You can find this option under “Configuration > PLC Runtime Services > CODESYS 2 > communication enabled”.

As general security measures strongly WAGO recommends:

1. Use general security best practices to protect systems from local and network attacks.
2. Do not allow direct access to the device from untrusted networks.
3. Update to the latest firmware according to the table in chapter solutions.
4. Industrial control systems (ICS) should not be directly accessible from the Internet, but should be protected by consistently applying the defense-in-depth strategy.

The BSI provides general information on securing ICS in the ICS Compendium (https://www.bsi.bund.de/SharedDocs/Downloads/EN/BSI/ICS/ICS-Security_compendium.pdf).

Remediation

We recommend all effected users to update to the firmware version listed below:

The vulnerability was reported by Daniel dos Santos and Abdelrahman Hassanien from Forescout.

Coordination done by CERT@VDE.