80% of all attacks come from within the enterprise - so the dogma.
After the Verizon report that stated that the insider threat is grossly exagerated here is another interesting piece from Taosecurity :
- Did you know that the 80% statistic is based on a 17 year old report with questionable procedures?
- Did you know that this is know since a 2001 CSI/FBI study quoted Dr. Eugene Schultz ? 
There is currently considerable confusion concerning where most attacks originate. Unfortunately, a lot of this confusion comes from the fact that some people keep quoting a 17-year-old FBI statistic that indicated that 80 percent of all attacks originated from the [inside].
- Quote: "For the past five years, incidents caused by insiders accounted for 7% or less of all Web intrusions. In 2003, outsiders accounted for 53%. About one-quarter of respondents said they “don’t know” the origin of their Web incidents, and 18% said “both” the inside and outside participated."
- While the 80% myth seems busted, insiders apparently caused more financial damages than outsiders.
Read more at TaoSecurity