Servers for Square Enix Co.'s popular online game "Final Fantasy XIV" has been hit by a series of cyberattacks since early October, preventing some users from accessing the service, its publisher said Thursday.
The distributed denial of service (DDoS) attacks, in which multiple hacked computers are used to flood the target system, were carried out to an "unprecedented extent" against data centers in Japan, North America and Europe, Square Enix said.
The identities of the attackers are not yet known, although information security experts suspect links to cheap online services that carry out so-called DDoS attacks.
Two major attacks in early October and late October prevented game players from logging in to the service or cut off their connections for up to 20 hours, according to the company.
Square Enix has taken steps against the attacks but the servers were attacked again Tuesday night, disrupting the service for some 50 minutes.
"FFXIV" had previously been subjected to DDoS attacks. A study by a U.S. internet company has showed that some 80 percent of DDoS attacks worldwide are targeted at game services.
"The attacks may have been carried out by people who commit the offense for pleasure, hold a grudge against the company or seek money," said Nobuhiro Tsuji, an information security expert.
"The attacks have extended over a long period, and, while it is costly, there is no choice but to boost countermeasures," the expert at SoftBank Technology Corp. said.
In 2014, a high school student in Kumamoto Prefecture was found to have used an online DDoS attack service to disrupt a different game company's operations after he became frustrated with the way the game services were managed. He was referred to prosecutors the same year.