Boro were denied a club clean sheet record and precious victory thanks to a controversial late leveller.
They went ahead early in the second half with a well-crafted goal from Mustapha Carayol and were on course for an eighth successive shut out at home when Darius Henderson bundled home an equaliser on 80 minutes - the first Boro had leaked at the Riverside in 11 hours and 54 minutes.
But Boro claimed the goal had gone in off the striker's hand and both keeper Dimi Konstantopoulos and closest defender Ben Gibson chased referee Roger East to protest.
Boro boss Karanka insisted that his players' reactions told the story.
"I could not see it and the replays are not conclusive," he said. "It is for the Forest player to explain if it hit his hand or not.
"But I think it was handball, for sure. You could see from the reaction of my players that they thought it was.
"These are not players who would normally chase the referee to complain and if they thought it was handball then 100 per cent I believe them.
"It was close to the record of clean sheets, yes, but I don't want to be speaking about records, only about wins and performances.
"We haven't played well today but we had two or three good chances to win this game against a very good side who are in the play-off places."
With boss Billy Davies banished to the stands and under a self-imposed press embargo, Forest assistant manager David Kelly spoke to the press.
He admitted he was not bothered if the leveller was a handball or not.
"At first look it seems as if he has hit it with his arm," he admitted. "But I haven't had time to ask Darius about it and to be honest I don't really care.
"We are disappointed a bit. We could've come in at half-time a few goals up and I thought we showed great spirit to come back into it after going behind.
"Given the way we played over the 90 minutes I thought a point was the least we deserved."