In an opening half of very few chances, Villa broke the deadlock in the 24th minute. Carlos Cuellar crossed from the left for Charles N'Zogbia, who sent a powerful effort beyond the reach of Rovers goalkeeper Paul Robinson.
Blackburn, who failed to register a shot on target in the opening 45 minutes, left the pitch to a chorus of jeers from the home support.
Ireland had the first chance of the second half, but again Robinson was on hand to parry the midfielder's low shot wide of goal.
Despite struggling to create throughout the match, Rovers secured a share of the spoils five minutes from time. Bradley Orr crossed for Dunn, who guided a header beyond the reach of Given.