Some really exciting statistics reported by Verizon Business RISK team.
It is worth to note the fact that although percentage-wise the insider data breaches are 18% compared to the external 73%, later in the report is is mentioned that impact of an insider breach is relatively a lot higher than of an external breach. Summary is below:
Who is behind data breaches?
73% resulted from external sources
18% were caused by insiders
39% implicated business partners
30% involved multiple parties
How do breaches occur?
62% were attributed to a significant error
59% resulted from hacking and intrusions
31% incorporated malicious code
22% exploited a vulnerability
15% were due to physical threats
What commonalities exist?
66% involved data the victim did not know was on the system
75% of breaches were not discovered by the victim
83% of attacks were not highly difficult
85% of breaches were the result of opportunistic attacks
87% were considered avoidable through reasonable controls
You can find the report here