Researchers find computer code that Volkswagen used to cheat emissions tests

May 22, 2017, University of California - San Diego
An international team of researchers uncovered the code that allowed Volkswagen to cheat US and European emissions tests. Credit: iStock/University of California - San Diego

An international team of researchers has uncovered the mechanism that allowed Volkswagen to circumvent U.S. and European emission tests over at least six years before the Environmental Protection Agency put the company on notice in 2015 for violating the Clean Air Act. During a year-long investigation, researchers found code that allowed a car's onboard computer to determine that the vehicle was undergoing an emissions test. The computer then activated the car's emission-curbing systems, reducing the amount of pollutants emitted. Once the computer determined that the test was over, these systems were deactivated.

When the emissions curbing system wasn't running, cars emitted up to 40 times the amount of nitrogen oxides allowed under EPA regulations.

The team, led by Kirill Levchenko, a scientist at the University of California San Diego will present their findings at the 38th IEEE Symposium on Security and Privacy in the San Francisco Bay Area on May 22 to 24, 2017.

"We were able to find the smoking gun," Levchenko said. "We found the system and how it was used."

Computer scientists obtained copies of the running on Volkswagen onboard computers from the company's own maintenance website and from forums run by car enthusiasts. The code was running on a wide range of models, including the Jetta, Golf and Passat, as well as Audi's A and Q series.

"We found evidence of the fraud right there in public view," Levchenko said.

During emissions standards tests, cars are placed on a chassis equipped with a dynamometer, which measures the power output of the . The vehicle follows a precisely defined speed profile that tries to mimic real driving on an urban route with frequent stops. The conditions of the test are both standardized and public. This essentially makes it possible for manufacturers to intentionally alter the behavior of their vehicles during the test cycle. The code found in Volkswagen vehicles checks for a number of conditions associated with a driving test, such as distance, speed and even the position of the wheel. If the conditions are met, the code directs the onboard computer to activate emissions curbing mechanism when those conditions were met.

A year-long investigation

It all started when computer scientists at Ruhr University, working with independent researcher Felix Domke, teamed up with Levchenko and the research group of computer science professor Stefan Savage at the Jacobs School of Engineering at UC San Diego.

Savage, Levchenko and their team have extensive experience analyzing embedded systems, such as cars' onboard computers, known as Engine Control Units, for vulnerabilities. The team examined 900 versions of the code and found that 400 of those included information to circumvent .

A specific piece of code was labeled as the "acoustic condition"—ostensibly, a way to control the sound the engine makes. But in reality, the label became a euphemism for conditions occurring during an emissions test. The code allowed for as many as 10 different profiles for potential tests. When the computer determined the car was undergoing a , it activated emissions-curbing systems, which reduced the amount of nitrogen oxide emitted.

"The Volkswagen defeat device is arguably the most complex in automotive history," Levchenko said.

Researchers found a less sophisticated circumventing ploy for the Fiat 500X. That car's onboard computer simply allows its emissions-curbing system to run for the first 26 minutes and 40 seconds after the engine starts— roughly the duration of many emissions tests.

Researchers note that for both Volkswagen and Fiat, the vehicles' Engine Control Unit is manufactured by automotive component giant Robert Bosch. Car manufacturers then enable the code by entering specific parameters.

Diesel engines pose special challenges for automobile manufacturers because their combustion process produces more particulates and than gasoline engines. To curb emissions from these engines, the vehicle's onboard computer must sometimes sacrifice performance or efficiency for compliance.

The study draws attention to the regulatory challenges of verifying software-controlled systems that may try to hide their behavior and calls for a new breed of techniques that work in an adversarial setting.

"Dynamometer testing is just not enough anymore," Levchenko said.

Explore further: French emissions probe clears Opel; others accused of fraud

More information: "How They Did It: An Analysis of Emission Defeat Devices in Modern Automobiles", The 38th IEEE Symposium on Security and Privacy in the San Francisco Bay Area on May 22 to 24, 2017.

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6 comments

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Moltvic
1 / 5 (2) May 22, 2017
One would think code such as this would be implemented into firmware...
tblakely1357
5 / 5 (2) May 22, 2017
I find it weird that Volkswagen thought that their cheat would never be discovered. And what about other manufacturers of diesel powered cars? Were their testing results similar to Volkswagen? If so, how without cheating themselves? I suspect there is a lot more to this scandal than is let on.
petey53
not rated yet May 22, 2017
If CEOs got imprisoned as punishment for violations you can bet companies would obey. Fines don't work on large companies. VW is barely hurting.
tblakely1357
3 / 5 (2) May 22, 2017
No but big corporations hate negative PR and cheating on emissions testing is a huge PR nightmare for them. While on the surface imprisoning CEOs might tickle your SJW streak, CEOs rarely know everything going on in a giant mutli-division corporation. Now if you want to go after the people who directly implemented the cheating, that's fine with me.
antialias_physorg
3 / 5 (2) May 23, 2017
I find it weird that Volkswagen thought that their cheat would never be discovered.

You have no idea how stupid (or greedy) managers can be. None. Even the smart ones will cause stuff to be implemented inthe hopes that it will be found only after they leave the company (which is currently a 3-5 year span on average for top level managers). I see in the comments this 'Volkswagen is hurting' or 'negative PR' - as if the people who perpetrated this stunt would care about the company. A company is made up of people. Identifying yourself with a company was a model that worked 50 years ago. But with the hire&fire-approach came the time of the self serving managers.

If CEOs got imprisoned as punishment for violations you can bet companies would obey.

Golden rule: He who has the gold makes the rules. Mangers should be slapped with fines, jail and forced labor from here to sundown. But it ain't gonna happen. Ever.
TheGhostofOtto1923
4 / 5 (4) May 23, 2017
Mangers should be slapped with fines, jail and forced labor from here to sundown. But it ain't gonna happen. Ever.
"What do Jeff Skilling, Bernie Ebbers, Dennis Kozlowski, John Rigas, Sanjay Kumar, Walter Forbes, Joe Nacchio, Richard Scrushy, Sam Waksal, and Martin Grass all have in common? They were all CEOs of prominent public companies, convicted of big-time corporate fraud and sentenced to lengthy prison terms.
They were all also fabulously wealthy when they committed their crimes."

- Your cynicism stems from not becoming management yourself perhaps?

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