AMX Harman, which makes a variety of audio-visual and building control equipment, has patched the problem. But on Thursday SEC Consult, an information security firm in Vienna, revealed what it says is the back story.
Last March, SEC Consult warned AMX that it had found a secret account in certain versions of the NX-1200, an appliance for controlling audio-visual systems.
The hidden account used the username Black Widow, and SEC Consult said it found the password as well by studying the appliance's authentication procedures.
The credentials can be used to gain broad access to the device, including the web-based management and command line interfaces. A hacker would also be able to capture packets, SEC Consult wrote.
The account appears to have been intentionally created, Johannes Greil, head of SEC Consult Vulnerability Lab, said via email.
"The backdoor is quite critical, because it seems to be deliberate and not some leftover from developers," he wrote. "The system tries to actively hide it from user management interfaces and the backdoor account even has more privileges than an admin account."
The finding by SEC Consult is worrying since AMX has a significant government business. In a photo on its website, it shows a photo of U.S. President Barack Obama with top advisors with the tag line "Room Automation."
Although it was notified in March, AMX didn't provide a fix until October. When SEC Consult analyzed the fix, they noticed the "Black Widow" account had simply been changed to a new username.
According to a security brief from AMX, it removed what it called the "debugging account" to prevent a security vulnerability.
SEC Consult said it hasn't checked to see if the latest fix is effective. It did not release the passwords for either of the hidden accounts.
A more detailed advisory from SEC Consult says that backdoors affect many other products besides the NX-1200. AMX officials could not immediately reached for comment.
Now that the issue has ostensibly been resolved, SEC Consult wrote that its contact at AMX said the company "will be starting a major security initiative."