The Internet server for the Web edition of the Nikkei daily and its Nikkei Asian Review recently came under cyberattack and was altered to direct viewers to other sites, which may have been infected with computer viruses, according to the daily and other reports.
Along with the Nikkei sites, those of several Japanese companies using the same server, which is based in the United States, were also altered in the same manner, the Nikkei said in a notice on its website dated Wednesday.
According to JPCERT Coordination Center, a Tokyo-based industry group providing information about Internet security, the latest attacks are believed those called "domain name hijacking," the Nikkei said.
Viewers may have been directed to other sites for several hours to a few days in September and October, the security body was quoted as saying.
An official at the center was quoted by NHK as saying it is extremely difficult for viewers to notice domain hijacking and defend themselves against potentional computer infections, adding that service providers bear great security responsibilities.