Microsoft acquired a number of Halo 7, Halo 8 and Halo 9 domains earlier this week.
According to Fusible, the platform holder picked up the domains halo7.net, halo7.org, halo8.org, halo9.net and halo9.org through internet brand protection company MarkMonitor.
Microsoft has confirmed a Halo 4 release date of November 6.
343 Industries has told CVG it already has "a definite story arc in mind" for Halo 5 and Halo 6.
A Microsoft job advert posted in July said the firm was seeking an experienced graphics developer to help create the "next generation of game visuals in the Halo universe" at 343.