Though attacks represent a large source of data breaches, negligence and computer errors are behind the majority of compromised information.

But attacks are significantly more serious. In 2009, the average cost of mopping up after a record stolen through malicious activity was $215 per document. But data compromised due to corporate negligence or systems glitches cost just $154 and $166 per record to remedy, respectively.

Last updated July 22 2011: 10:59 AM ET
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