Security watchdog the Computer Emergency Response Team (Cert) has warned that the amount of malicious activity on the web is climbing at an alarming rate.

It reported that the total number of attacks in 2001 climbed almost 160 per cent compared to the previous year.

Based at Carnegie Mellon University, and partially funded by the US federal government, Cert said that virus outbreaks, network attacks or inside abuse accounted for 52,658 incidents reported in 2001, compared with 21,756 in 2000. Cert documented 9,859 reports in 1999, and 3,734 in 1998.

Chad Dougherty, a security analyst at Cert, said that the rise in incidents could be attributed to increased sensitivity and awareness as to what defines an incident. There are also more people looking for vulnerabilities and the potential for incidents.

In addition, Cert found that there were 2,437 vulnerabilities reported in 2001, a massive increase from the 1,090 reported in 2000. Of that number, 13 per cent, or 326, were serious enough for Cert to issue advisories warning the public of the problem.

Microsoft had a large share of the vulnerabilities reported in 2001, as both Code Red and Nimda targeted the company's Internet Information Server software.

Cert has been documenting statistics since 1988 when it responded to merely six incidents and released one security alert.