Hundreds of Vietnamese websites, mostly those of government agencies and state offices, have been attacked by hackers over the last few days, according to HVAOnline security forum.
The attacks started on June 2, targeting website addresses ending in "gov.vn."
The hackers penetrated into the websites through security holes and left messages written in Chinese and English on the home pages.
Many of the websites were paralyzed because of distributed denial-of-service attack (DDoS attack).
According to HVAOnline, the attacks on the websites with the domain name "gov.vn" are decreasing but other domain names are still being targeted by the hackers.
As of press time, a number of websites have yet to be restored.
Vietnamese security forums have warned administrators of the websites to regularly backup data, and develop ways to cope with hackers.