Researchers at Tencent's Keen Security Lab have published more details major security holes in Tesla's firmware, which attackers could use as a full attack chain to control vehicles.

The company posted the details of the vulnerabilities in a blog last week, which found that the attack chain could implement arbitrary CAN BUS and ECUs remote controls. In other words, attackers could control the vehicles remotely.

In 2016, Keen Lab conducted multiple tests on Tesla Model S vehicles, which found that attackers could potentially control vehicles in both park and drive move. Researchers said at the time that it was the first case they knew of that used CAN BUS compromises to achieve remote controls.

Last month, Tesla CEO Elon Musk was quoted at a US National Governors Association meeting as saying that cybersecurity in Tesla vehicles is a major priority.

He said that a fleet-wide hack could be a potential reality, but manufacturers have to make that impossible. He suggests that override authority is the way to do that.

In September last year, Tesla also implemented a security process called ‘code signing', which was designed to conduct integrity checks of firmware. Keen Labs was able to bypass the code signing.

Musk also said that there are some sub-systems such as braking and powertrains that have multiple levels of encryption, which means attackers can't gain control of those systems.

Keen Lab researchers say they followed 'responsible disclosure' processes so that Tesla had time to verify and confirm all bugs in the report.

Researchers also found a number of zero-days in different vehicle modules. While those vulnerabilities haven't been properly documented yet, they are working with Tesla and other manufacturers to assign CVE numbers. CVE numbers are given to every vulnerability found.

Tesla says that most of the affected vehicles have now been patched and updated via firmware-over-the-air (FOTA).

Researchers are urging Tesla owners to check that their vehicle's firmware has updated to version 8.1 (17.26.0) or later. If not, update systems immediately.

Tesla also encourages security researchers to report security vulnerabilities.

“Tesla values the work done by security researchers in improving the security of our products and service offerings. We are committed to working with this community to verify, reproduce, and respond to legitimate reported vulnerabilities. We encourage the community to participate in our responsible reporting process,” the company says on its website.

Here's how Keen Labs researchers managed to take control of a Tesla vehicle.