What type of security incident is characterized by classified data being introduced into an unauthorized information system?

The correct response identifies "spillage" as the specific type of security incident where classified data is inadvertently or intentionally introduced into an unauthorized information system. This situation is particularly critical because it poses serious risks to national security and can lead to unauthorized access to sensitive information.

Spillage occurs when classified or sensitive data that is meant to be contained within secured systems is mistakenly or carelessly released into less secure environments. This often results from human error, such as misplacing or incorrectly handling information, or it may arise from insufficient security measures in place to prevent such occurrences.

Understanding this term is essential in the context of information security within the Department of Defense, as it underscores the importance of stringent controls and safeguards around classified data. Addressing spillage is crucial to mitigating risks associated with potential insider threats or external breaches, as once classified information leaks into unauthorized domains, it becomes accessible to entities that should not have it.

This distinction is vital for anyone monitoring information security practices, as recognizing and responding to spillage effectively helps maintain the integrity of sensitive data and the security of overall systems.