2. What is Computer Virus?
• Computer viruses are small software
programs that are designed to spread
from one computer to another and to
interfere with computer operation.
3. Spreading of Viruses
• Usually disguised as something else
(e.g. Instant Messaging messages, Funny images,
Audio and Video Files, Downloading files from
Internet, Greeting cards and many more.)
• Cause unexpected and usually
undesirable events
4. Spreading of Viruses (cont.)
• Often attached to files
• Deliver a “payload”
(e.g. display a message, delete or modify a
document, reformat hard drive)
5. Spreading of Viruses (cont.)
• Does not spread itself from computer to
computer
– Must be passed on to other users through:
• Infected e-mail document attachments
• Programs on flash drives
• Shared files
6. Macro Viruses
• Most common and easily created viruses
• Created in an application macro
languages
(e.g. Visual Basic or VBScript)
• Infect documents
• Infect application templates
7. Famous Virus: Melissa
Melissa attacked computers in March 1999, infecting machines when
users opened a Word document attachment.
Through the effect the virus had on individuals’ computers was
minimal, users of Outlook Express unintentionally sent virus on to
first 50 people who where in their Global Address Book.
For companies, however, the virus had a larger impact.
The virus was sent to users with the subject “Important message from
[name].”
More than a million users were infected, the BBC reported.
Also caused $80 million in damage, and was first virus to travel
through e-mail.
8.
9. Prevention
• Use an Internet firewall
• Subscribe to industry standard antivirus
software
• Never open an e-mail attachment from
someone you don’t know
• Scan each and every attachment
