Congressional Research Service (via Federation of American Scientists)
PDF - http://www.fas.org/sgp/crs/terror/RL33123.pdf
"This report examines possible terrorists’ objectives and computer vulnerabilities that might lead to an attempted cyberattack against the critical infrastructure of the U.S. homeland, and also discusses the emerging computer and other technical skills of terrorists and extremists. Policy issues include exploring ways to improve technology for cybersecurity, or whether U.S. counterterrorism efforts should be linked more closely to international efforts to prevent cybercrime."
