‪Google was not attacked, instead the network you are accessing through is the attacked, and you were blocked because of that.

‪And since i can't think of any possible network other than your ISP and KACST i think it's unlikely to happen since both of them are running Unix flavors.

‪So the possible thing is one of the Saudi corporates that run Micro$oft windows was attacked by a virus that hits it's loads on Google and for your bad luck you were accessing through the same proxy (i.e. proxy.jed10.isu.net.sa).