A security expert at SEC Consult discovered that some WAGO industrial managed switches are affected by several serious vulnerabilities.

A security researcher at consulting company SEC Consult discovered several vulnerabilities in some models of WAGO industrial switches.

The vulnerabilities affect WAGO industrial switches 852-303, 852-1305 and 852-1505 models. The company has already fixed the issues with the release of firmware versions 1.2.2.S0, 1.1.6.S0 and 1.1.5.S0, respectively.

“The industrial managed switch series 852 from WAGO is affected by multiple vulnerabilities such as old software components embedded in the firmware. Furthermore, hardcoded password hashes and credentials were also found by doing an automated scan with IoT Inspector.” reads the security advisory. “Two vulnerabilities (CVE-2017-16544 and CVE-2015-0235) were verified by emulating the device with the MEDUSA scaleable firmware runtime. The validity of the password hashes and the embedded keys were also verified by emulating the device.

One of the most severe issues is related to the presence of hardcoded credentials that can be used to connect the devices via Telnet and SSH.

“Hardcoded Credentials (CVE-2019-12550) – The device contains hardcoded users and passwords which can be used to login via SSH and Telnet.” continues the advisory.

The expert also found hardcoded private keys for the SSH daemon in the device’s firmware. An attacker can use them to carry out man-in-the-middle (MitM) attacks against the Dropbear SSH daemon without the victim noticing any fingerprint changes.

“The device contains hardcoded private keys for the SSH daemon. The fingerprint of the SSH host key from the corresponding SSH daemon matches to the embedded private key.” states the advisory.

SEC Consult also discovered that WAGO industrial switches use outdated versions of the BusyBox UNIX toolkit and the GNU C Library (glibc). Both libraries are affected by known vulnerabilities, some of which rated as critical.

Experts suggest restricting network access to the device and SSH server in order to protect the system. The good news is that affected switches are not exposed online.

The German VDE CERT has published an advisory to warn of the flaws in the WAGO devices.

Pierluigi Paganini

(SecurityAffairs – Wago industrial switches, hacking)

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