Rather, Tesla built its MOS software to automate factory processes for assembling the Model 3, its newest vehicle. In general, MOS is used to track where a Model 3 is in the process of manufacturing, repairs and testing.

First, this is not software that's installed in Tesla's vehicles. If anyone modified MOS code, they were not changing the code embedded on chips in Tesla's cars.

Tesla declined to comment for this story. However, CNBC talked to former employees and looked at current employees' job descriptions on LinkedIn, and new job listings from Tesla on Ladders, to learn a little bit about it.

So what is this MOS (or TMOS) software that Tesla is talking about?

Tesla is suing a former employee , Martin Tripp, for allegedly hacking into its MOS factory software, transferring several gigabytes of company data to outside entities and making false claims to reporters. Tripp disputed the charges.

Specifically, factory workers can log details into the MOS about whether or not the body of a Model 3 is completely assembled, whether specific items have been installed (such as steering wheels, air bags or rocker mold), and the torque levels used on factory equipment to put the Model 3s together. MOS also tracks whether each car has gone through necessary repairs, quality and safety testing before it leaves the factory.

Workers also use MOS in the production of Tesla's home energy storage product, the Powerwall, and its battery packs. As such, Tesla's Fremont, California plant, its Gigafactory 1 in Sparks, Nevada, its factory in Buffalo and another one in Ireland all use MOS.

This software is just one of many reporting systems used within the electric vehicle and clean energy company.

For example, Tesla also runs a program called MES (its "manufacturing execution system") to support the production of its Model S and X vehicles; the Tesla Executive Factory dashboard to show equipment effectiveness and line data, and to show high-level production numbers to executives; and something called Garage (or Garage Portal) to see which firmware updates drivers have gotten or may need.

A former employee said that repair notes and other data can sometimes get lost across these disparate programs, sometimes leading to duplicate work.

A long-time investor in enterprise tech companies, Trinity Ventures General Partner Ajay Chopra, said it's uncommon for large manufacturers to roll their own ERP -- or enterprise resource planning -- software. Most buy software from the likes of SAP and Oracle, and heavily customize it.

Chopra sees Tesla's MOS as a potential revenue generator for the company.

"When Amazon developed AWS that was slated for in-house use. But over a decade, it's become the standard for all cloud services. Elon Musk's vision is paralleling that, I'd guess. He's betting that the factory of tomorrow will be very different than it is today, because cars are becoming more software than hardware. There should be some continuity from manufacturing to the car, where you are updating and bringing new features out over the air. And it all has to be served up by the ERP system."