The spyware used in cyberattacks on Vietnam's major airports and national carrier last month is now also suspected of having bombarded many more official sites amid tensions with China over territory in the South China Sea.

Malicious code disguised as anti-virus software has been found lurking in everything from government offices to banks, major companies and universities, and was the same as that used in "politically colored" attacks on two of the country's biggest airports and Vietnam Airlines, said Ngo Tuan Anh, vice chairman of Hanoi-based network security company Bkav Corp.

On July 29, the flight screens at the airports displayed messages critical of Vietnam's claims to the South China Sea, according to the VnExpress news website. Vietnam and the Philippines have been the most vocal in criticizing China for its increased assertiveness over the area.