The government has stepped up its vigilance against possible cyber attacks from North Korea.
  
Part of the efforts include a ban on public officials’ use of commercial e-mail services and tighter checks on major state infrastructure facilities following a recent circulation of several abnormal e-mails that Seoul believes were sent out by the North.
   
The government has also asked the public to stay alert and keep their personal computers or smartphones safe by installing the latest antivirus software and not opening suspicious e-mails.
 
The government upgraded its cyber security alert level by one notch from “normal” to “attention” on its five-tier scale on January eighth following the North’s fourth nuclear test.