Old Concept of attack,spread virus with the help of exe files or even some files with different extension.Same methodology is used but instead of using exe files pdf files are used to spread the virus.Main drawback is user need not even click on anything its enough if you open the pdf file.This is more or less similar to a worm but the only difference is worm will spread on its own but to spread this kind of virus user have open the pdf file
Earlier, virus was spreading with the help of acrobat software,software used to create PDF documents.Most important thing is its also possible to hack your computers with the help of this acrobat reader.If a pdf file is going to be a virus then its possible to install some bad software on your system and after which the system information and all the other details can easily be hacked from your personal computer or laptop
McAfee has also released some patches to identify this virus and also to destroy it but not to the full extent