Photo/IllutrationU.S. cybersecurity authorities issue a warning about the Emotet computer virus. (From the US-CERT website)

More than 400 organizations in Japan have been infected by a computer virus that is wreaking havoc around the world, a cybersecurity organization in Tokyo revealed on Nov. 27.

According to the Japan Computer Emergency Response Team Coordination Center (JPCERT/CC), many organizations infected with the Emotet virus were small and midsize companies. As an increasing number of them are requesting help, the number of cases of damage is expected to increase.

Emotet is attached to e-mails by attackers posing as trusted parties, such as actual people or organizations known to the recipient. When the attachment is opened, the computer becomes infected.

The virus steals e-mail addresses and texts and creates new spoof messages with them.

An increasing number of cases of damage due to the virus in Japan have been reported since October, including at educational institutions.

At Tokyo Metropolitan University, a spoof e-mail was sent to a teacher's computer by an attacker pretending to be a person from an actual publishing company on the morning of Oct. 18.

The company publishes a journal that previously carried a research paper by the teacher.

The same afternoon, a new spoof e-mail was sent to another person in the university by an attacker posing as the teacher, after which the infection was discovered.

Dozens of messages pretending to be from the teacher were sent to others.

The spread of the powerful and self-propagating virus all over the world was confirmed in September, with governmental organizations in the United States and Australia issuing warnings.

As the virus attacks are sophisticated, JPCERT/CC analyst Hayato Sasaki believes that the infection is widespread.

Attackers pretend to be persons who can be trusted like a client and send e-mails in the form of a reply for the previous e-mails.

"If you have received a suspicious e-mail, please tell the person described as the sender and ask him or her to take measures against the virus," Sasaki said.