Computer Virus

What is a Virus
is an unwanted Program or application

Make copies of itself


Carry out a particular action



How infection occurs

Infected floppies and CD's

Email and Internet

Launch file and the virus code runs

Copy itself and Make changes

Infected removable flash device

Trojan Horses

Seemingly legitimate programme

With hidden function (harmful)

May be a programme that causes a virus infection

Backdoor Trojans allow other users to take control of a PC across the Internet


Similar to viruses

Make copies of themselves

Use email to spread

Spread throughout networks

Kakworm, Sircam, Badtrans

Effects of Viruses

  1. Display messages, Pranks
  2. Deny access to files
  3. Data theft (email information)
  4. Corrupt Data (change spreadsheets), Delete data
  5. Disable hardware (Chernobyl)

Virus Risks

Internet: downloaded programs or documents

Programs, Email with attachments

Documents and Spreadsheets

Floppy disks and CDs

Preventing viruses

Make users aware of the risks

Install anti-virus software and Update software regularly

Keep backups of all data

Use of Anti virus Software

Detects viruses

Prevent access to infected files

Eliminate infection

Scanners (must be updated)

On demand

On access stay active on machine

Heuristics (uses general rules to detect viruses)


Love Bug

Email: I love you: kindly check attached love letter coming from me

Worm that sends itself to others in your address book

Steals information and overwrites files

Recent Viruses in Education

Kakworm: Includes itself in all outgoing emails

Magistr (sends files) deletes windows files

Sircam (hi I need your advice) Cant open programs

Badtrans Single click needed

Side effects of viruses

Prevent computers from working

Cost money to sort out, Time consuming

Confidentiality at risk, Damage...