Democracy Is Strengthened by Casting Light On Spending in Elections Act of 2017 or the DISCLOSE Act of 2017 This bill amends the Federal Election Campaign Act of 1971 (FECA) to ban campaign contributions and expenditures by corporations that are controlled, influenced, or owned by foreign nationals. The bill redefines the term "independent expenditure" to include an expenditure that is the functional equivalent of express advocacy because it can be interpreted by a reasonable person only as advocating the election or defeat of a candidate. The bill expands the period during which certain communications are treated as electioneering communications. The bill prescribes disclosure requirements for campaign-related disbursements by corporations, labor organizations, and other entities, including a political committee with an account established for the purpose of accepting donations or contributions that do not comply with the contribution limits or source prohibitions under FECA.