UNSC Military Security Code 447-R27
From Halopedia, the Halo wiki
United Nations Space Command Military Security Code 447-R27 is a UNSC protocol enforced in 2552. It forbids a consultant from accessing classified files. AIs guard the database against this. In event of an infraction, the offense is recorded and authorities are immediately notified. The AI then warns the infractee to stop, and is authorized to use whatever force necessary if the infractee will not comply. Dr. Catherine Halsey and her AI Kalmiya broke this protocol during the Fall of Reach when they accessed Colonel James Ackerson's secure files in ONI's CASTLE Base on planet Reach, which led Halsey to the SPARTAN-III program on Onyx.
When players in the Hunt the Signal competition found links to all the pages early, the page that had 447-R27.com as a URL updated to have this security code taking effect. This was to stop players finishing the competition so quickly.
List of appearances