Top ten viruses reported to Sophos in April 2001

Sophos Press Release

This is the latest in a series of monthly charts counting down the ten most frequently occurring viruses as compiled by Sophos, a world leader in corporate anti-virus protection.

For April 2001, the chart is as follows, with the most frequently occurring virus at number one:

Position Last
Malware Percentage of reports

"April's top ten is dominated by the Magistr worm," said Graham Cluley, senior technology consultant at Sophos Anti-Virus. "This virus is particularly notable because it contains its own SMTP client and so doesn't rely on using Outlook or other email programs to spread. However, it does rely on users opening it once it arrives so the message to users is simple - don't open unsolicited attachments."

April also saw the payload date of the Chernobyl (CIH) virus. Every year on April 26th (the anniversary of the Chernobyl incident) the virus attempts to overwrite infected systems' hard disks and wipe their BIOS chips, effectively leaving computers unusable. The virus was first seen in June 1998 and caused significant amounts of damage to computers in April 1999 and April 2000. This year saw fewer reports of the virus than in previous years - even so, clearly many people have failed to keep their anti-virus protection sufficiently up to date.

1288 new viruses were discovered and protected against by Sophos during April 2001.

The total number of viruses Sophos detects and protects against is 63,180.

Compiled by Sophos's technical support team, the top ten chart is collated from calls to Sophos's 24 hour, 365 days a year technical support line.

Graphics of the above Top Ten chart are available here.

More than 100 million users in 150 countries rely on Sophos’ complete security solutions as the best protection against complex threats and data loss. Simple to deploy, manage, and use, Sophos’ award-winning encryption, endpoint security, web, email, mobile and network security solutions are backed by SophosLabs - a global network of threat intelligence centers. Sophos is headquartered in Oxford, U.K., and is publicly traded on the London Stock Exchange under the symbol “SOPH.” More information is available at