Technically yes, but it is not recommended. The file is tied to Steam DRM. If your friend's copy is cracked, you will be flagged. If it is legitimate, Steam will still verify the file and may replace it anyway. You are better off verifying your own files.
This is the safest, most reliable method. download iw6sp64shipexe install
Steam will scan your folder, find the missing iw6sp64_ship.exe , and download a fresh, clean copy. 2. Reinstalling from Physical Media Technically yes, but it is not recommended