By Ruben Santamarta @reversemode
The Industrial Control Systems Cyber Emergency Response Team (ICS-CERT) this Friday published an advisory about some backdoors I found in two programmable gateways from TURCK, a leading German manufacturer of industrial automation products.
Using hard-coded account credentials in industrial devices is a bad idea. I can understand the temptation among manufacturers to include a backdoor “support” mechanism in the firmware for a product such as this. This backdoor allows them to troubleshoot problems remotely with minimal inconvenience to the customer.
On the other hand, it is only a matter of time before somebody discovers these 'secret' backdoors. In many cases, it takes very little time.
The TURCK backdoor is similar to other backdoors that I discussed at Black Hat and in previous blog posts. The common denominator is this: you do not need physical access to an actual device to find its backdoor. All you have to do is download device firmware from the vendor's website. Once you download the firmware, you can reverse engineer it and learn some interesting secrets.