Please see the authorized How to use ComboFix
Next you should download ComboFix from one of the following URLs:
To download ComboFix, simply left-click on one of the links above...Click on the Save button, and when it asks you where to save it
If you intend to run ComboFix on your own due to malware infection, please be aware that using ComboFix is only one part of the disinfection process. Preliminary scans from other tools like DDS
should be used first because they provide comprehensive logs with specific details about files, folders and registry keys which may have been modified by malware infection. Analysis of those logs allows planning an strategy for effective disinfection and a determination if using ComboFix is necessary. ComboFix was never meant to be used
as a general purpose malware scanner like SuperAntispyware or Malwarebytes' Anti-Malware which scan individual drives or different folders on a computer for viruses.
I ask that you heed our warning about using this tool on your own without proper supervision.