DHS Acquisition Authorities Act of 2017 This bill amends the Homeland Security Act of 2002 to designate the Department of Homeland Security's (DHS's) Under Secretary for Management as DHS's Chief Acquisition Officer. Such officer's duties shall include: (1) establishing acquisition policies that implement an approach that takes into account risks of failure to achieve cost, schedule, or performance parameters for all DHS components; and (2) ensuring that each major acquisition program has a DHS-approved acquisition program baseline. The bill specifies criteria governing the Under Secretary's delegation of acquisition decision authority to the relevant Component Acquisition Executive for such programs. The bill sets forth the responsibilities of DHS's Under Secretary for Science and Technology with respect to operational testing and evaluation of such programs. The bill includes among the responsibilities of DHS's: (1) Office of Program Analysis and Evaluation, ensuring that acquisition program costs are in accordance with budget estimates and are affordable, or can be adequately funded, over their life cycle; and (2) Chief Information Officer, ensuring that information technology acquisitions comply with DHS's information technology management processes, technical requirements, and the Homeland Security Enterprise Architecture, providing recommendations to an acquisition review board within DHS regarding information technology programs, and developing information technology acquisition strategic guidance. The bill establishes within the Management Directorate of DHS a Program Accountability and Risk Management Office to: (1) provide consistent accountability, standardization, and transparency of major acquisition programs; and (2) serve as the central oversight function for all DHS acquisition programs.