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Researcher says he's found hackable flaws in airplanes' navigation systems

April 11, 2013 at 11:56 AM ET

Here’s an uncomfortable image to keep in mind during your next flight: A rogue hacker who can redirect planes at will with the touch of an Android phone’s screen.

That’s the frightening scenario laid out by Hugo Teso, a security researcher for the German IT consultancy N.Runs, in a presentation at the Hack In The Box security conference in Amsterdam Wednesday. By hijacking a protocol used to send data to commercial aircraft and exploiting bugs in flight management software built by companies including Honeywell, Thales and Rockwell Collins, Teso told the crowd that he could send radio signals to planes that would cause them to execute arbitrary commands such as changes in direction, altitude, speed, and the pilots’ displays.

“You can use this system to modify approximately everything related to the navigation of the plane,” Teso told me in an phone interview following his talk. “That includes a lot of nasty things.”

Read the latest about the researcher who says he's found hackable flaws in airplanes' navigation systems

Update: Several companies and aviation safety organizations now claim that Teso’s research wouldn’t work on actual airplanes. See their comments below.

Hackers and security researchers have warned for years of vulnerabilities in next-generation air traffic control protocols. But Teso focused on a different protocol called Aircraft Communications Addressing and Report System, (ACARS) a simple data exchange system that has evolved over decades to now include everything from weather data to airline schedules to changes to the plane’s flight management system. (FMS)

Teso says that ACARS still has virtually no authentication features to prevent spoofed commands. But he spent three years reverse engineering the flight navigation software that receives ACARS signals to find bugs that allowed him to send his own commands to the systems, either from a software-defined radio that can be tuned to use ACARS or from a compromised airline system. In his talk, Teso demonstrated an Android application he built that allowed him to redirect a virtual plane with just a tap on a map application running on his Samsung Galaxy phone. “ACARS has no security at all. The airplane has no means to know if the messages it receives are valid or not,” he says. “So they accept them and you can use them to upload data to the airplane that triggers these vulnerabilities. And then it’s game over.”

In his presentation, Teso explained that he experimented on used FMS hardware he bought from eBay and FMS training simulation software that was advertised as containing some or all of the same code as the systems in real planes. In our interview he declined to specify exactly what vulnerabilities he discovered in that code, saying that he has instead contacted the Federal Aviation Administration (FAA) and the European Aviation Safety Administration, (EASA) and is working with the affected aerospace companies to fix the problems.

Honeywell, for its part, confirms that it’s been talking to Teso’s employer. But spokesperson Scott Sayres argues that Teso’s work doesn’t necessarily prove any real vulnerabilities in Honeywell’s equipment or software. “We take this seriously and we’re going to work with N.Runs to assess this,” says Sayres. “But as Teso readily admits, the version he used of our flight management system is a publicly available PC simulation, and that doesn’t have the same protections against overwriting or corrupting as our certified flight software.”

Teso’s supervisor at N.Runs, fellow security researcher Roland Ehlies, counters that the vulnerabilities Teso found in the FMS software weren’t related to the PC version he was testing, but rather to functions that would also exist in real planes. “From our perspective it would work with at minimum a bit of adaptation,” he says.

I’ve reached out to Rockwell Collins, Thales, the EASA and the FAA for comment and will offer an update if I hear back from them.

Update: Spokespeople for the EASA, FAA and Rockwell Collins all echo Honeywell’s statement that while Teso’s attack works on PC simulation software, it wouldn’t give him control of a real plane’s certified flight management system. I’ve included their statements at the bottom of the story.

The increased use of mobile devices in the flight deck, however has introduced new risks. To minimize and eliminate these potential vulnerabilities, we’re prototyping enhanced security features and collaborating with industry regulators, customers and suppliers to develop new standards that will assure the highest levels of protection.”

Both Honeywell’s Sayres and Teso agree that even if a hacker were able to alter the FMS through commands remotely sent over ACARS, the pilots of the plane should be able to override those malicious commands with their own valid ones. Nonetheless, Teso said in his presentation that at the very least, a hacker could perform disruptive stunts like causing the cockpits’ lights to blink wildly or the passengers’ pressurized air masks to drop.

Teso’s presentation is far from the first to raise the potential for hackers to disrupt air travel. Two talks at the Black Hat and Defcon security conferences last summer suggested that hackers could spoof or intercept signals sent using the next-generation air traffic control system Automated Dependent Surveillance-Broadcast or ADS-B. That trick might allow an attacker to suddenly generate the appearance of a non-existent plane in a pilot’s direct path, potentially causing chaos in the air.

Tricks with ACARS to disrupt or hijack planes’ flight management systems–if they bear out in real world tests beyond those Teso has performed–could be far more dangerous. Teso believes that the bugs he’s discovered in those navigation systems can be fixed. In the meantime, those in the cockpit would be wise to keep an eye on their autopilot.

Update: As noted above, aviation safety groups and the FMS software makers have taken issue with Teso’s claims. Their statements are copied below.

The EASA: “For more than 30 years now, the development of certifiable embedded software has been following strict guidance and best practices that include in particular robustness that is not present on ground-based simulation software.”

Rockwell Collins: “”Today’s certified avionics systems are designed and built with high levels of redundancy and security. The research by Hugo Teso involves testing with virtual aircraft in a lab environment, which is not analogous to certified aircraft and systems operating in regulated airspace.

The FAA: “The FAA is aware that a German information technology consultant has alleged he has detected a security issue with the Honeywell NZ-2000 Flight Management System (FMS) using only a desktop computer. The FAA has determined that the hacking technique described during a recent computer security conference does not pose a flight safety concern because it does not work on certified flight hardware. The described technique cannot engage or control the aircraft’s autopilot system using the FMS or prevent a pilot from overriding the autopilot. Therefore, a hacker cannot obtain “full control of an aircraft” as the technology consultant has claimed.”

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