The attackers have as yet not leaked any of the company's data on their web site on the dark web.
DFJ's parent company pulled in revenue of Increase €7.341 billion (A$11.8 billion) in 2019, according to Wikipedia. The total number of employees the same year was 12,757.
Contacted for comment, a company spokesman said in a statement that the attack had been noticed on 7 December (Monday).
"The attack was isolated to DFJ servers based in the United States. It does not include any data from parent company Dassault Aviation.
"Some company systems are not affected and are functioning normally while others have been impacted to varying degrees. French and US IT teams and their cyber security partners are working diligently to restore the affected systems to their full capacity.
"In the interim, all departments have implemented contingency plans to ensure our customers’ and employees’ needs are addressed properly.
"Global deliveries of new Falcons for the remainder of 2020 will be maintained."
Ragnar Locker was recently used to attack the Indian company Biological E, which received a grant of US$4 million (A$5.49 million) from the Gates Foundation to develop a COVID-19 vaccine.
Other companies to be affected by the same ransomware are Italian liqueur manufacturer Campari Group and Japanese game maker Capcom, French transport and logistics firm CMA CGM Group and US travel management company CWT.
CWT agreed to pay a ransom of US$4.5 million (A$6.3 million) in bitcoin to the attackers.
According to the global cyber security firm Sophos, Ragnar Locker now has the ability to attack virtual machines.