Target detection for a multi-static passive radar, in which the radar uses multiple illuminators of opportunity, as well as multiple target surveillance receivers, is considered. It is shown that this detection problem can be formulated as a statistical test of whether a signal of known rank is present in both the reference and target surveillance channels, or only in the reference channels, in the presence of independent gaussian white noise across all channels. Bayesian and generalized likelihood ratio tests for target detection are derived for both known and unknown receiver noise variances and are compared through simulation.