Microsoft Excel is prone to a remote code execution issue which may be triggered when a malformed Excel document is opened. The issue is due to an error in Excel while handling malformed URL strings. There may be other ways to trigger this vulnerability. Successful exploitation could allow an attacker to execute arbitrary code with the privileges of the user running Excel. Code execution is dependent upon certain factors including the overflow condition, the MS Excel version and the host OS and SP. If you cannot get it to work, attach it with the debugger check the stack layout and the rest is on your imagination. Compile with MS VC++ or g++, it will generate the Excel file. Clicking the link in the file binds the shell, C:nc localhost 4444.