Abstract: Highly undetectable steganography (HUGO) is one of the most advanced steganographic systems. A new methodology of steganalysis is presented against HUGO for digital images. The proposed method first obtains textural features by applying local linear transformation of convolution filtering to the image. Then, the co-occurrence matrices are constructed from horizontal and vertical direction. Finally, the ensemble classifier is used to classify. Experimental results show that the proposed steganalysis system is significantly superior to the prior arts on the detection performance and computational time.