Depending on the swiftness of his recovery, the 22-year-old could be back in contention for Ulster's back-to-back Heineken Cup encounters with the Ospreys on December 7 and 14.
Ferris picked up the injury playing for Ireland during the summer tour's second Test against Argentina last June. On his return from the tour, an arthroscopy was performed on his knee and he was deemed fit to be included in the Ireland World Cup squad.
Prior to his World Cup selection, he played in the warm-up match against Scotland in August but failed to force his way into any of the Ireland matchday squads during the tournament.
Since his return from France, the Maghaberry youngster has played three times for Ulster in the Magners League - including two 80-minute efforts against Leinster and Glasgow Warriors in recent weeks.
However, the injury has been flaring up for him and even with careful management, he has been unable to train with the province. The Ulster Rugby medical staff have decided that, in the player's long term interest, Ferris must rest for a period of four to six weeks to allow the injury to settle.
Meanwhile, the news regarding flanker Kieron Dawson's leg injury, which saw him stretchered off against Glasgow last Friday, is more positive and the former Ireland international is expected to be included in the Ulster squad for tomorrow's all-ticket clash with Gloucester (Ravenhill, kick-off 8pm).