This paper establishes generic existence of a unique equilibrium in the symmetric two-player binary-signal all-pay auction with arbitrarily correlated signals and interdependent valuations. Further, it provides a complete characterization for all parameter values and proves that the equilibrium is symmetric and weakly monotone. In equilibrium, the bid supports are ordered by the strong set order, and yet the bid supports of a low signal player can overlap with that of a high signal player. Hence, in a symmetric weakly monotone equilibrium, a bidder with a low signal can outbid a high signal player. Applying the model to elections shows that a candidate receiving good news from the polls behaves in a rationally overconfident manner, making it possible for the other candidate to win the election in an upset.