Companies have in place their own firewalls and anti-virus software to protect data stored on the premises.

CNN: How safe is cloud computing?

Frequent updates of the data files associated with antiviral software can protect users from known viruses.

CNN: Technology - Analysis: Understanding viruses

They can also invest in other tools like AirDefense Personal, software which sits on a laptop computer and helps protect data when a worker is using his computer wirelessly while traveling.

FORBES: How Lehman Brothers Overcame Its Wireless Fears