Six examples - How employee accounts could be compromised.

Everyone knows compromised accounts are hard (not impossible) to detect. 

One of the problem is that employees don't like it when their accounts have lesser privileges as they presume it is related to trust or prestige.

According to the article:- 

By the standards of today's black market for thieves, your employees are in the cross-hairs for some of the most serious attacks on your company.

Updates, you can do. Vulnerabilities can be patched. But people... are people.

(here is the sorry state)

76 percent of breached organizations needed someone else to tell them they've been hacked . Employee awareness could be worth more than the latest anti-malware software, and will save you millions in the race to prevent cyber theft. (Trustwave, 2013)

The links below has more information:-

http://www.zdnet.com/six-clicks-how-hackers-use-employees-to-break-through-security-walls-7000027755