Excel and Word, as part of Microsoft Office XP or Office 2003, have an option to password protect the file. Sometimes you may need to recover a forgotten password, or to test the strength of a password.
I use the following free utility whenever I need to brute force these Office passwords:
Free Word / Excel Password Recovery Wizard offers the same functionality and performance as expensive commercial Word password / Excel password software, but is a completely free download. Unlike other supposedly "free" downloads, it is a full product, not a demo version or shareware. It contains no spyware or other malware.
We developed our own free password recovery package specifically to address the high cost of commercial password software.
Our easy to use software runs on any Windows 9x and later PC and recovers file open passwords (not sheet passwords though) for Word / Excel 97 to Word / Excel XP 2003 files. It works by trying words from a large dictionary (included with the download) against the file, then tries character combinations to find most common file open passwords.