He has returned to running in training but Ferris revealed he will not have a good idea of when he's likely to make his comeback with Ulster for approximately a month.
"I'm back running on the pitch now but it's been so long since I've actually ran, it's a lot of work," Ferris told the Belfast Telegraph.
"We haven't put a timetable on the recovery the whole way through and that's still the case but after another four or five weeks on the pitch doing some running and we should have a much better idea of when I'll be able to get back out there."
Ferris' lengthy spell on the sidelines has meant that he has been unable to add to his 35 Ireland caps - the last of which was won against England at Twickenham in 2012.
But he remains in the minds of the current Ireland squad, including captain Paul O'Connell, who missed the victory over Scotland last Sunday with a chest infection.
He added: "Paul O'Connell texted me two minutes before kick-off saying that he was sat there feeling sorry for himself that he couldn't play and then he thought of me."
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