A new type of cyber-attack that sends data to internet service providers' servers via home routers has caused internet failures in at least 4.8 million households since spring, The Yomiuri Shimbun learns.
The internal affairs and telecommunications ministry is calling on users to update software for their home routers.
This particular cyber-attack is called a "DNS amplification attack" and is a type of distributed denial of service (DDoS) attacks, which cause servers to go down by sending a massive amount of data.
Under the DNS amplification attack, an attacker sends data to an ISP's servers via home routers as some types of home routers respond to communications from outside. The data is amplified several dozen times when being sent to the servers.
The attacker overloads the servers by repeatedly sending data to the targeted home routers and eventually cripples those servers.