NEW YORK — A computer virus that spread to more than a million computers worldwide, including some at NASA, and produced at least $50 million in illegal profits or losses to victims should be a ‘‘wake-up call’’ for banks and consumers unaware of the threat posed by Internet criminals, a prosecutor said Wednesday.

US Attorney Preet Bharara and George Venizelos, head of the New York FBI office, warned of the growing threat to financial and international security as they announced that a 2½-year probe had resulted in three arrests, two of them overseas.