Here's what we know about Hive, the group that may have shut down MediaMarkt systems

MediaMarkt was the victim of a hack attack this week.

According to research by

, the attack was carried out by Hive, a hacking group that often strikes large companies and even hospitals.

The gang also struck earlier in the Netherlands.

Hive is a fairly new hacking group.

After a hack on software company Altus last summer, the group first came into the picture.

The hackers leaked company data because no ransom was paid.

Since then, investigative services have had Hive in their sights.

The hacking group attacks companies, taking files hostage, rendering their computer systems useless.

The group is known for being thorough and also deleting backups of victims' computers so that they cannot be easily restored.

It is unknown who is behind the group.

It is also not clear from which country or countries the group operates.

Not all hacking groups attack all companies just like that.

Some groups explicitly do not focus on companies in the critical infrastructure, such as electricity companies, hospitals or educational institutions.

Hive does not make this distinction and has successfully launched attacks on such targets.

In August, for example, Hive took hospital systems hostage in the US.

As a result, surgical procedures and radiological examinations could not proceed.

Company in Zwolle also hacked by Hive

The group also carried out attacks in the Netherlands.

Research by NU.nl shows that computers of a company in Zwolle were hacked by the group in October.

The company says the damage was limited, because it had well-secured backups.

Once the computer systems are shut down, Hive demands ransom from its victims.

The group would now demand 50 million dollars (43 million euros) in ransom from MediaMarkt.

If the company declines, computers will remain encrypted and stolen files may be put online.

Intrusion via phishing emails

According to the FBI, which issued a warning about the group in August, the hackers are sending phishing emails to companies, including infected files.

In the emails, Hive often pretends to be another company.

If an employee bumps into Hive's mail, the group can gain access to the company's network.

The group is also trying to gain access via a system that allows remote computer systems to be controlled, the so-called Remote Desktop Protocol (RDP).

Hackers with their own helpdesk

Hive is a professional gang and has built websites to communicate with victims.

These sites are on the dark web, the closed off part of the internet.

Once the hacking group has attacked a company, it leaves files on the encrypted computers.

These files contain login details that allow victims to contact the hackers on their website.

The ransom is then negotiated through a special section of that site.

Victims are also often shown evidence that Hive is actually behind the attack and that the hacking group is able to release the encrypted computers.

Through the site, affected companies must pay with bitcoins.