Source – wsj.com As more companies unplug their data centers and rent out cloud-computing services from providers such as Amazon.com Inc. and Microsoft Corp. , some are discovering an unexpected problem: They’re accidentally leaving their corporate data exposed for all the world to see. Configuration errors made while using cloud-storage services are common, security experts say, and often occur when users set access permissions so someone outside of the company—say, a vendor—can see data. “More data has been lost due to poor configuration than anything else on