Hacker groups Anonymous and LulzSec have made a name for themselves by scanning large organizations until they find the one weak system ready to be exploited. You can prevent an attack.
The virtual environment is very different from the "physical" data center where networks, servers and applications can be easily secured and monitored.
Visa has issued best practices that detail how retailers, card issuers and processors can upgrade their credit card transaction technology to a chip-based model, so to avoid burdensome complexity, cost and time to market.