Dealing with Insider Threats
Detection: use intrusion detection systems; however, they are not perfect (high false positives rate).
Prevention: use access control, firewalls, proactive security; but vulnerabilities still exist (OS bugs, buffer overflow, cover channels, etc).
Mitigation (tolerate/cope): use mechanisms that provide service to correct participants while under attack, even if several participants are compromised.
The above methods do not exclude each other.