But Chubb has been listed on the attackers' website, the first step they follow after a successful attack.
According to its own website, Chubb had more than US$177 billion (A$291 billion) in assets and reported US$40 billion of gross premiums in 2019. The company says it has offices in Zurich, New York, London, Paris and other locations, and has more than 30,000 employees.
iTWire contacted Chubb's Australian office for comment. A spokesperson responded: "We are currently investigating a computer security incident that may involve unauthorised access to data held by a third-party service provider.
"We have no evidence that the incident affected Chubb's network. Our network remains fully operational and we continue to service all policyholder needs, including claims. Securing the data entrusted to Chubb is a top priority for us. We will provide further information as appropriate."
There is no statement on the company's website to indicate that an attack has taken place.
Like every type of Windows ransomware attack, Maze encrypts files on a Windows system and then displays a ransom note to the user.
Maze Ransomware group apparently hacked Chubb, a huge insurance company (worth $50 Billion) and are blackmailing them.— Under the Breach ? (@underthebreach) March 26, 2020
- Haven't posted proof for these claims yet. pic.twitter.com/JoUgQl47wV
But an additional tool in its armour is that Maze exfiltrates data from its victims and then uses that data to pressure the victim to accede to its ransom demand.
Under the Breach told iTWire that the attackers had tagged the Chubb chief executive Evan Greenberg, chief operating officer John Keogh, and vice-chairman John Lupica in the note on their website, adding that this was an indication that the main website, chubb.com, had been attacked.
A screenshot from the Maze website was tweeted by Under the Breach at about 4am AEDT on Friday. No date has been given for the attack, merely that it took place this month.
This is the second Maze attack that iTWire has reported in the last fortnight. Last Thursday, a report said the Maze group had attacked Australian freight forwarding and logistics firm Henning Harders.
A follow-up to that on Monday said the attackers were pressuring the company to pay up by publishing some data which had been exfiltrated after the attack.
A Henning Harders spokesperson told iTWire on Monday: "It does not follow that because a company remains fully operational despite a cyber incident that a ransom has been paid."