Even if the ISO is authentic, it may be an early build without any service packs. Windows 7 RTM (Release to Manufacturing) is missing critical updates, drivers for modern hardware, and has known vulnerabilities that have been exploited for years.
: A broader directory listing of various Windows 7 ISO images. Chuvash State University Software Index
intitle:"index of" "windows 7 ultimate" iso
: Contains original MSDN files for Professional and Ultimate (x86 and x64). Windows 7 ISO Directory Listing