Sure, and it would work with tech we have today.
Cancers generally start when radiation damages DNA. This is able to occur because radioactive particles can permeate, or pass through, a majority of substances - including flesh.
Lots of radiation exposure increases the likelihood that eventually, one of those particles will hit the right part of a DNA strand within one of a multitude of cells - stopping the cells from regulating their deaths, forming tumors, and so on.
If CRISPR is programmed to identify the DNA that regulates healthy cell death and damage it - and it spreads like a virus through host cells - then this idea is completely feasible with modern technology.
Once scientists identify that a virus is responsible for the mass cancer outbreaks, they will likely create a vaccine, or a countervirus that repairs cells - or even just cure cancer anyways after they have increased funds to do so - so not only did you fail, but you indirectly cured cancer.