The vulnerability affects the Tridium Niagara AX Framework, and lets remote attackers access the system's configuration file that contains login credentials for operator work stations, through which the attackers can gain complete control of electricity and HVAC systems, elevators, surveillance cameras, electronic door locks and more.
In order to get root access to the system, the researchers have concatenated two distinct bugs, and then used a specially crafted backdoor module to be able to "stay" in it.
The attack can't work on systems that are not directly accessible from the Internet, but unfortunately many are. By using the Shodan search engine, the researchers discovered over 21,000 Tridium systems facing the Internet.
Tridium has been notified of the flaw and they are working on a fix that should be released by February 13.
"The vast majority of Niagara AX systems are behind firewalls and VPNs - as we recommend - but clearly, as Rios and McCorkle have shown, there are many systems potentially at risk," commented Tridium spokesman Mark Hamel.