The Information Security Department (Hebrew: המערך לביטחון מידע, HaMa'arakh LeVithon Meida, abbreviated to Mahbam) is a department in the Israel Defense Forces' Directorate of Military Intelligence, responsible for preventing classified information from being compromised by unauthorized elements. It was formerly known as the Field Security Department.

The Department engages in the study of enemy military intelligence, providing security briefings, securing classified information, and teaching and enforcement activities related to information security. Most of the security breaches that take place are in the area of computing (including the Internet), and the securing of documents. The Department absorbs about 450 new Information Security NCOs annually. Its members serve in all branches of the IDF.