Andy Rodgers came off the bench to rescue a point for Dumbarton after Forfar had looked likely to take home all three with a smash-and-grab act.
The Sons dominated the first half but failed to take their chances. Chris Boyle drove narrow wide in the early stages while Loons' keeper Michael Brown, who had a real Jekyll and Hyde afternoon, saved well from a Barry Donald volley and an Ian Dobbins header.
After the break play continued to flow towards the visitors' goal, and Brown produced an outstanding one-handed save to keep out a close-range header by Dobbins.
However, with their first meaningful shot at goal, Forfar went in front. A long ball from midfield was taken on the run by Paul Tosh and from 18 yards he gave Stephen Grindlay no chance as the Sons' defence appealed in vain for hand-ball.
The home side looked rattled but they were gifted an equaliser when David Dunn – under no pressure – slipped on the edge of the box and newly-introduced substitute Rodgers pounced on the loose ball to fire home under the diving Brown.
Both sides could have snatched it in a furious closing spell which saw Brown save well from a Rodgers snap-shot while, at the other end, Forfar were denied a last-minute penalty when Tosh went down in the box under a Derek Allan challenge.