The MIL-STD-1553 data bus standard has been in wide usage in avionics since the 1970s. Its versatility has made it an integral part of aircraft communication in commercial and military applications, which holds even today. For starters, it can communicate with up to over two dozen remote terminals simultaneously over dual physical layers. It’s also compatible with a wide array of both new and old communications tools and modules such as PCI Express and is best known for its fault tolerance. MIL-STD-1553 tutorial, intelligent interface cards & more >>

On the flip side, 1553 was never designed to be secure. The security features of 1553 (or the lack thereof) have potentially tainted its reputation in the aerospace and defense industry.

Cybersecurity is a growing menace to network-connected systems such as military and commercial flight avionics. Hackers have managed to find different ways to attack interconnected computers and gain access to them to steal or sabotage critical flight data. For all its features, MIL-STD-1553 is a vulnerable standard that can pose a risk to the functioning of avionics and the safety of critical flight data.

Thankfully, there are ways to strengthen and secure connections made using standard 1553. While they are not foolproof, they help build a system surrounding 1553 that’s impervious to cyberattacks. Here’s one such way of using digital flight simulator data to make MIL-STD 1553 secure for avionics applications.

Cyber Defense for 1553 Data Bus: Why Is It Needed?

MIL-STD-1553 and its iterations were never meant for securing flight avionic data. The reason for their implementation even today is their high backward and forward compatibility, accuracy, and ability to handle robust interconnections. There is no security infrastructure involved in standard 1553.

The connections between line replaceable units such as radars and sensors, engine controls, and other cockpit management devices are held together by 1553 without any form of a security layer. There is no form of authentication or encryption involved in these connections.

Cyber sleuths can find a vulnerability in any of these connections and attempt to gain access. All such attempts to hack into avionics systems are currently curtailed at the entry level (frequency and systems monitoring), but it’s nowhere near an ideal solution.

Although, MIL-STD-1553 was last updated in 2007 that replaced the standard’s word parity check with a built-in checksum feature. While this helps prevent false positives or errors in aircraft communication, it does very little to make its connections secure.

It is this lack of a security infrastructure that makes 1553-driven systems prone to cyberattacks.

The Challenge in Securing 1553

The default 1553 standard does not allow any adjustments or security implementation. There are two reasons for this:

  • 1553 systems already in operation cannot be tweaked as they all have different configurations.
  • Old standards and components connected to 1553 systems will still pose a risk.

The only two ways, therefore, to implement a security infrastructure to a system running 1553 are:

  1. Improve the security features of modern standards and components connected to 1553.
  2. Choose secure components in new configurations and installations.

One of these involves looking at possible vulnerabilities brought about by a 1553 system in an artificial simulation environment. Once this data is available for assessment, the task would be to introduce security policies and/or add new embedded systems that come with default authentication, logging and warning systems, and attack mitigation.

Here’s how Excalibur’s Flight Sim package offers engineers a way to get simulated flight data to aid in their attempt to make 1553 secure.

1553 Cyber Protection Solution: Using Flight Simulator Software

In 2021, Excalibur launched the Flight Sim package that allows you to gather data from a flight simulator software (like the Microsoft Flight Simulator (MFS)) and relay it to avionics interfaces. It’s compatible with MIL-STD-1553 and other standards such as ARINC 429 and ARINC 717.

The Flight Sim setup requires a protocol converter like Miniature Airborne Communications Converter (MACC) to translate the simulation data which is extracted as an Ethernet stream from the software. The extracted data can then be tested against the 1553 standard to look for possible security gaps. How these gaps are filled depends on the type of application, budget, and scenario.

The advantage of using Flight Sim is that it allows you to generate real-life flight scenarios. This can give a virtual overview of what security precautions such a 1553 system needs to take to avoid or prevent a cyberattack.

Excalibur’s decision to choose MFS as the partner has to do with its rich database of real-life flight and airport information. For instance, it includes avionics descriptions of thousands of aircraft as well as commercial and military airports around the world. This makes it easier to simulate any flight and get its equivalent data.

Using flight simulation software to study the avionics of a purported flight gives you a clearer picture of the flight’s path. If you anticipate a cyberattack over a certain airspace, then you can implement additional security protocols in that route to make the 1553 system safer.

Here’s how one of our customers used our Flight Sim package to improve 1553 cyber security and mitigate potential hacking attacks. 

Case Study Using Flight Sim Package by Excalibur

Our client developed a set of algorithms to detect any anomalies in an avionics system that could thwart potential cyberattacks. The algorithm set looked good on paper, but they wanted to test it out in real time. Implementing it on an actual avionics system and running it would have cost them a lot of money. Especially when they knew it was only going to be an experiment. Due to their novel invention, it was also not possible to estimate the odds of success.

They reached out to Excalibur to help them simulate a real-life flight scenario so that they could test out their 1553 cyber protection algorithm. Here’s what they did.

Step 1 – Create a flight simulation and add external anomalies to it

They used our Flight Sim package to set up a flight simulation for a regular flight path. They implemented their set of algorithms into the code and let the simulation run. They also wanted to set up external anomalies that would disturb the system avionics during the flight.

The trouble was that there was no way to implement the anomalies. If you’ve worked with flight simulation data before, you’d know that it’s not easy to change a binary data file. Even if you managed to do so, the end product would either not be accepted by a data reader or reconstructor or would result in a bad reading.

Step 2 – Input anomalies to flight simulation data

This is where Flight Sim helped our client the most. First, they used our Flight Sim package to generate the flight data. Next, they used our Unet 2 device to monitor this collected data. Third, they employed our Data Reconstructor to rebuild the simulated data.

We had to add a feature to our package which helped the client convert binary data into a CSV file. This is so that they can easily read and edit it. This is the feature that helped the client add anomalies to the reconstructed data and then go back to Unet 2 to observe if their algorithm system did what was expected of it.

If you observe, the client did not have to write a single line of code to test out their anti-cyberattack system. All they did was use our Flight Sim package to get real-life flight data. The fact that they required some customization and we were able to provide it shows how flexible Flight Sim is for real-life avionics system testing.

Are you looking to improve cyber defense for 1553 data bus for your avionics systems? Check out our Flight Sim demo and get in touch with us today.