Making
This includes the writing or creation of computer viruses, worms, trojans, malware, malicious scripts etc.
Supplying
This 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.
Obtaining
If 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.
This part of the Act is known as 3A.