The main danger related to the way Moodle implements file uploads is potential distribution of virus infected files. There are two major groups of viruses—classic binary virus which distributes itself in form of executable program, and macro virus which spreads itself through document files and templates.
A computer program capable of copying itself by infecting other executables during its execution is called a virus. They are always targeted to a particular type of Operating System, so viruses written for Microsoft Windows will not run on Apple OS X and vice versa.
Document files are usually infected with so-called macro viruses. Macro viruses are computer viruses written in document application programming macro language. Unlike standard viruses which infect executable files (other programs), these ones infect documents and document templates. Document types that are most affected are those produced by Microsoft Office suite. The most...