Attacks on web servers and the defacement of web pages have risen by 36 per cent over the past year, according to a cyber-crime observation group.

Zone-H recorded 392,545 attacks on web servers worldwide during the past 12 months, in which hackers used the web servers for their own purposes or defaced the contents.

"Defacement is just one option for an attacker. In most circumstances the techniques used by defacers are the same as those used by criminals to cause more serious damage," said Zone-H founder Roberto Preatoni.

"The collection of this information on cyber-crime provides data for the evolution of trends and the definition of techniques, allowing system administrators to test their own servers and close the security holes."

Preatoni warned that, once VoIP phones become ubiquitous, the problems will get worse if similar web architecture is used. Hacked phones could be used as remote control snooping devices or for industrial espionage, he said.

The survey found that nearly 50 attacks were made against US military servers, and 186 attacks against US government servers. Worldwide 3,918 government domains were attacked last year.