SAN FRANCISCO — A security loophole that would allow someone to add extra steps to the counter on your Fitbit monitor might seem harmless. But researchers say it points to the broader risks that come with technology’s embedding into the nooks of our lives.

On Tuesday, a group of computer security researchers at the University of Michigan and the University of South Carolina will demonstrate that they have found a vulnerability that allows them to take control of or surreptitiously influence devices through the tiny accelerometers that are standard components in consumer products like smartphones, fitness monitors and even automobiles.

In their paper, the researchers describe how they added fake steps to a Fitbit fitness monitor and played a “malicious” music file from the speaker of a smartphone to control the phone’s accelerometer. That allowed them to interfere with software that relies on the smartphone, like an app used to pilot a radio-controlled toy car.

“It’s like the opera singer who hits the note to break a wine glass, only in our case, we can spell out words” and enter commands rather than just shut down the phone, said Kevin Fu, an author of the paper, who is also an associate professor of electrical engineering and computer science at the University of Michigan and the chief executive of Virta Labs, a company that focuses on cybersecurity in health care. “You can think of it as a musical virus.”