This paper deals with the problem of detecting distributed targets in the presence of homogeneous and partially homogeneous Gaussian disturbance with unknown covariance matrix. The proposed detectors improve the adaptive beam-former orthogonal rejection test (ABORT) idea to address detection of distributed targets, relying on the generalized likelihood ratio test (GLRT). Remarkably, the newly proposed detectors can guarantee the constant false alarm rate (CFAR) property with respect to the unknown quantities. The performance assessment, conducted by Monte Carlo simulation, has confirmed the effectiveness of the newly proposed detectors.