United, who twice trailed the Black Cats had piled on their customary late pressure without result.
But, with just over two minutes of the four of injury time left, Michael Carrick clipped the ball into the Sunderland box. As others seemed to hold back, Antonio Valencia retrieved what looked like a lost cause by the right by-line.
His cross back into the centre was headed on by Wayne Rooney, but cleared by the Sunderland defence.
Patrice Evra latched on to it on the left side of the penalty area and his shot looked to be going wide until Ferdinand lunged at the ball at the far post and steered it into the back of his own net.
Sunderland had harried and hassled United throughout and set the agenda with a goal after seven minutes.
Kenwyne Jones, on the right corner of the United box, worked the ball back to Lee Cattermole who found Darren Bent on the right side of the penalty area.
Bent cut back inside before hitting a crisp right-foot shot from 20 yards into the bottom corner of the net.
The goal - Bent's seventh in the Premier League this season - would have been noted by watching England manager Fabio Capplelo who names his squad for the World Cup qualifier in Ukraine tomorrow.
United stirred but Sunderland remained unshaken, although the Reds should have had a penalty in the 36th minute when Luis Nani's cross was handled by Andy Reid in the box. Referee Alan Wiley remained unmoved.
Sunderland braced themselves for a more determined United in the second half and they were not to be disappointed.
The Reds equalised with an exquisite goal in the 51st minute. John O'Shea's cross from the right found Dimitar Berbatov 12 yards out and he scored with a magnificent right-foot overhead volley.
Sunderland came back to regain the lead seven minutes later.
Reid's measured clip into the box saw Jones rise with United goalkeeper Ben Foster to win his aerial challenge and head home from ten yards.
The Black Cats had former United man Kieran Richardson sent off with five minutes left.
Richardson, booked for a 29th minute foul on Danny Welbeck, kicked the ball away after a free-kick had been awarded to United and his departure would eventually cost his side two points.