Computer Misuse Act 1990

The Computer Misuse Act (1990) recognises the following as offences:

  1. Unauthorised access to computer material
  2. Unauthorised access with intent to commit or facilitate a crime
  3. Unauthorised modification of computer material.
  4. Making, supplying or obtaining anything which can be used in computer misuse offences.

Computer misuse act.

Unauthorised access to computer material

This is the lowest level of offence and is one that many of us might be guilty of at some stage in our school or working lives.

Have you ever found, guessed or used someone else’s password to log onto their user area? If you do this and then look at their files, even if you don't change, delete or damage anything, you are still guilty of accessing materials without authorisation - and this is illegal.

This offence carries the risk of being sentenced to six months in prison and/or a hefty fine.

Unauthorised access with intent to commit or facilitate a crime

The difference between this and the first offence is that the person gaining access to someone elses' system is doing so with the sole purpose of doing something illegal.

This might mean that they had to guess or steal the password in order to get into someone's user area or their bank account. They could do this by:

  • trial and error
  • using special programs such as spyware or keylogging software
  • using a relatively new technique called 'phishing'

They might want to steal some company secrets or they might want to transfer some money out of your bank account into their own.

Anyone caught doing this risks up to a five year prison sentence and/or a hefty fine.

Unauthorised modification of computer material

Everyone deletes files from their own system, maybe they no longer need them or maybe they delete them by mistake. This is fine - there was no intent to cause any damage.

This offence relates to the deletion or changes made to files with the intent to cause damage to an individual or company. The difference is 'the intent to cause damage'.

This offence also covers purposely introducing viruses to other peoples' systems.

If you knowingly transmit a virus to others, you are guilty under this section of the Computer Misuse Act.

This offence carries a penalty of up to five years in prison and/or a fine.

Making, supplying or obtaining anything which can be used in computer misuse offences

MakingThis includes the writing or creation of computer viruses, worms, trojans, malware, malicious scripts etc.
SupplyingThis part covers the distribution of any of the above material whether you have created it yourself or obtained it from elsewhere. It is an offense to supply or distribute these files to others.
ObtainingIf you purposely obtain malicious files such as as computer viruses or scripts that you know could be used to damage computer systems then you have committed an offence under the Computer Misuse Act.