Downloading "cracked" versions of games is a violation of copyright laws in most regions.
While many sites offer torrent downloads for older titles, downloading copyrighted software via torrents often carries risks: download-call-of-duty-4-modern-warfare-torrent-game-for-pc
If you are looking for the updated version with improved graphics, check for Call of Duty: Modern Warfare Remastered . Downloading "cracked" versions of games is a violation