Signal Detected. Tag Designation: Foe
From Halopedia, the Halo wiki
The teaser starts with black screen with a crack on it. A "!" icon appears and vanishes. Then an "Anomaly" message appears with the United Nations Space Command logo in the lower right hand corner. A "Deciphering" loading screen appears and finishes causing the transmission to start. With the screen turning Blue to Red.
The Banished Logo then appears in the middle of the screen, then the teaser glitches out.