Experts at SophosLabs™, Sophos's global
network of virus and spam analysis centers, report that the
malicious family of Mytobs continues to grow. New variants are
being pushed out by the virus writers, using a variety of tactics
to try and infect computers around the world.
In the last 24 hours, the Mytob family have accounted for 58% of
all reports to Sophos with 14 Mytob variants in the top 20 threats
currently infecting computers.
The most widespread variant of the family, Mytob-AS, was
first seen and protected against on Friday, 10 June and is
responsible for 15% of the reports. Mytob-AS is not only spread via
email, it also scans the internet for computers who haven't patched
against a variety of Microsoft security loopholes, such as the
"Patching against operating system vulnerabilities has never
been more important," said Carole Theriault, security
consultant at Sophos. "With a growing number of threats designed to
steal sensitive and confidential information, computer users want
to ensure that their barriers are up and ready to thwart these
The Mytob worms turn off security programs on infected Windows
computers and deny access to many popular security websites. They
also attempt to open a backdoor onto the computer, allowing
unauthorised remote hackers to gain access.
"There is nothing to suggest that the slew of Mytobs are tailing
off just yet," continued Theriault.