MIST 2017 the **9th ACM CCS International Workshop on Managing Insider Security Threats, Dallas, USA, Oct. 30 - Nov. 3, 2017 (Submissions due 4 August 2017) During the past two decades, information security technology developments have been mainly concerned with intrusion detection to prevent unauthorized attacks from outside the network. This includes hacking, virus propagation, spyware and more. However, according to a recent Gartner Research Report, information leaks have drastically increased from insiders who are legally authorized to access corporate information. The unauthorized leak of critical or proprietary information can cause significant damage to corporate image and reputation, perhaps even weakening its competitiveness in the marketplace. On a larger scale, government and public sectors may suffer competitive loss to other nations due to an internal intelligence breach. While the leaking of critical information by insiders has a lower public profile than that of viruses and hacker attacks, the financial impact and loss can be just as devastating. The objective of this workshop is to showcase the most recent challenges and advances in security and cryptography technologies and management systems for preventing information breaches by insiders. The workshop promotes state-of-the-art research, surveys and case analyses of practical significance. Physical, managerial, and technical countermeasures will be covered in the context of an integrated security management system that protects critical cyber-infrastructure against unauthorized internal attack. We expect that this workshop will be a trigger for further research and technology improvements related to this important subject. For more information, please see http://isyou.info/conf/mist17