Preventing insider attacks
Dealing with insider threats is possibly one of the most difficult tasks facing an information security practitioner today. However, best practices implemented correctly can help mitigate this threat. In a properly designed network, users would only have access to the information that is necessary for their jobs.
To read more go here - http://blog.trendmicro.com/trendlabs-security-intelligence/insider-threats-101-the-threat-within/