Visitors to Yahoo's Web pages who clicked on ads the past few days
are potentially at risk of having their computers infected by malware,
according to published reports Sunday.
Fox IT -- an Internet
security firm that discovered the alleged malware infection -- says
300,000 users were visiting the infected ads every hour. That means
roughly 27,000 computers and devices were being infected every hour
since typically 9% of computers are actually infected after visiting the
site. Most computer users either use software that combats such
infections or may have configured their computers to be resistant to the
Malware, short for malicious software, is software used
to disrupt computer operation, gather sensitive information, or gain
access to private computer systems. Computers connected to a network
can spread the malware onto many more computers. The malware may have
started spreading on Dec. 30.
This is just the latest technical problem to hit the struggling Yahoo
as it attempts to become more relevant as online services proliferate.
The company's e-mail service experienced widespread outages and problems
in late December.
Consumers should know that this Yahoo malware
attack works by redirecting clicks to ads on Yahoo to an infected site,
which then uses security holes in Oracle's Java to install malware. Java
is a commonly used "plug in" designed to add additional computational
capability to Internet browsers.
The infected site proceeds to
install a variety of malware to the user's device including those called
ZeuS, Andromeda, Dorkbot, Tinba or Necurs, Fox IT says. Most of the
users affected have been in Great Britain, France and Romania.
statement, Yahoo said it is aware of the security issues. The infection
rate has declined significantly, indicting that Yahoo is making
adjustments to fix the problem, Fox IT says.
Computer users can
protect themselves from this and other similar attacks. Perhaps the
easiest form of defense is turning off the Java plug in, which is
commonly installed in most browsers including Internet Explorer, Chrome,
Firefox and Safari. Internet Explorer users can easily turn off Java by
clicking on the icon that looks like a gear in the upper right-hand
corner of the screen and selecting "Manage add-ons." Under the "Add-on
Types," look for a section titled Oracle America, Inc. Right-click on
any entry that starts with the word Java, and choose Disable. Oracle
took ownership of Java following its acquisition of Sun Microsystems
closed in 2010.
Any computer users concerned they might be infected should run a scan of
their computer. Microsoft provides a free scanning tool called the Microsoft Safety Scanner that is able to detect and remove most malware.