The terms and classification schemes used in the computer security field today are not standardised. Thus the field is hard to take in, there is a risk of misunderstandings, and there is a risk the scientific work is being hampered. Therefore this report presents a proposal for a taxonomy of software based IT weapons. After an account of the theories governing the formation of a taxonomy, and a presentation of the requisites, seven taxonomies from different parts of the computer security field are evaluated. Then the proposed new taxonomy is introduced and the inclusion of each of the 15 categories are motivated and discussed. The final part of the report contains a discussion of the general defences against software weapons, together with a presentation of some open issues regarding the taxonomy. Finally the report is summarised.