A German researcher demonstrated the technique using Amazon’s Elastic Compute Cloud and their new cluster computing service that is designed for CPU-intensive graphics and password cracking are remarkably similar from an algorithmic perspective. Using a botnet or IaaS cloud, an attacker can now achieve in minutes or hours what would have taken years to try out in parallel. Using just 49 minutes of a single cluster instance, the researcher was able to crack passwords up to six letters in length using just $2.10 for one hour.
Source: https://thehackernews.com/2010/11/cloud-computing-best-for-password.html