Dexter Blackstock put Forest ahead when he broke into the area before Danny Graham chipped over Dorus de Vries before half-time.
Both teams remain nine points clear of third bottom MK Dons, who drew 0-0 at Sheffield Wednesday, and have a vastly inferior goal difference.
Forest are 18 goals clear of MK Dons with Blackburn 22 goals clear.
The hosts' lead lasted only seven minutes to deny caretaker boss Paul Williams victory, as Forest's winless run stretched to eight games.
Home supporters were cheered by the sight of a 10-minute cameo from the returning Britt Assombalonga - his first outing in 14 months after a knee injury - but they left largely frustrated as their lack of a cutting edge cost them again.
Blackstock got a helping hand from Hope Akpan's sloppy pass 35 yards from goal, raced forward and hit a rather tame-looking shot past Jason Steele, who could only help it on its way into the net.
But Steele twice denied Henri Lansbury, with the Forest skipper also skimming the crossbar from distance.
Nottingham Forest caretaker boss Paul Williams:
"We created lots of chances and in the second half, only one team wanted to win the game. On another day we would have scored two or three more goals.
"We're getting there in the style of football we want to play with the lads we've got.
"I'm not frustrated, I'm pleased with the way the lads played tonight. With a bit more luck, the goals will start to come."
Blackburn manager Paul Lambert:
"It is a great place to come and play, the pitch is fantastic and I thought a draw was fair.
"We dominated the ball in the first half and there was a lot of plusses tonight.
"We hit the bar, they hit the bar and there wasn't really much in it."
Nottingham Forest and Blackburn Rovers all but secured their Championship safety after sharing a draw.