BetaArchive (betaarchive.com) maintains a massive FTP server of abandonware, including all versions of Office. You must join the forum and have a certain number of posts to gain FTP access, but the files are curated and verified.
If you have landed on this page, you are likely looking for a specific technical resource: an This search string is a powerful one. It uses the "index of" directive to locate open directory listings on web servers, combined with a request for a verified, untampered ISO image of Microsoft Office 2007. index of ms office 2007 iso verified
The presence of .md5 or SHA1SUMS files is a strong indicator that the uploader cares about verification. BetaArchive (betaarchive