Viruses and Trojans

1
Viruses and Trojans

• Someone writes a virus
• A virus is a malicious program which can
  interfere with your computer and change the way
  it works, such as the ILOVEYOU virus shown here.

2
Viruses and Trojans

• The virus infects your PC
• A virus can enter your computer from an infected
  computer via an email attachment, or disguised as
  part of a download (though commercial websites
  are usually OK).

3
Viruses and Trojans

• The virus executes
• A virus or trojan 'executes' (i.e. runs) on your
  computer it can cause problems.  
• Viruses destroy files or slow down your operating
  system.  
• Trojans give hackers access to your computer -
  allowing them to steal passwords, copy files and
  read your email.

4
Viruses and Trojans

• Anti-virus companies update their software
• Once an anti-virus software company discovers
  that a new virus has been created, they give it a
  'signature' to identify it, update their
  anti-virus software to recognise it, and where
  possible remove or quarantine the virus.

5
Viruses and Trojans

• Virus detected
• When you go online your anti-virus software
  should automatically check for virus updates and
  download them in order to protect your computer
  against new threats, and to let your email and
  internet run safely.