W32/Perrun, also known as Perrun, comes in two parts. One file executes the virus body which is contained in another infected JPEG file or a file with a .JPG file extension. The virus arrives in the form of an executable, or .EXE file. Infected JPEGs are unable to replicate on non-infected machines – i.e. machines without the extractor component installed. There is no mass-mailing component and the code is not triggered unless a .EXE file is opened – i.e. there is no risk in opening a JPEG file.
Network Associates says that the virus “is a proof of concept and it has not been seen in the wild.” The virus would need some basic developments to pose a serious threat.