NetSky-P and Zafi-B continue to be the most frequent causes of computer virus infestation months after their releases in March and June this year. NetSky-P accounted for more than a third (35.8 per cent) of all viral incidents monitored by anti-virus firm Sophos in October. More than a quarter (28 per cent) of other reports compiled by Sophos were about Zafi-B.
The variety of social engineering tricks used by Zafi-B accounts for its relative success, according to Sophos. Emails infected with Zafi-B appear appended to text messages in many different languages, a factor that may have induced many, used to English-language only worms, into opening Zafi's infectious attachment. Only one new virus - Bagle-Zip - made in it into Sophos' monthly viral charts.
"With only one new entry, at the bottom of this month's chart, the dominance of Netsky-P and Zafi-B seems unshakable," said Carole Theriault, security consultant at Sophos. "These viruses are so prevalent and well established that it is very difficult for newer viruses to compete. Thousands of copies are circulating all over the world - it may be that unprotected PCs in areas where computer security is not a top priority are responsible for keeping the menace alive."
Sophos analysed and protected against 1,131 new viruses in October, bringing the total number of viruses Sophos protects against to 96,156. Sophos reckons that 4.6 per cent (or one in 22 emails) circulating in October were viral. That makes October a quiet month. By comparison almost one in ten emails (nine per cent) sent out in July were infected with a computer virus. ®
Top ten viruses in October 2004, according to Sophos