Msosync.exe is the Microsoft Office Document Cache. It enables the caching of Office 2010 documents. For example, documents uploaded to SkyDrive are cached by msosync.exe in the local drive for faster viewing. That
does not mean "when its on poeple can connect to my computer via that process". Given that your fears about what it does are unfounded and, in fact, it enhances your system's performance, why do you want to stop it? Doing so will degrade performance without providing any increase in security.
For detailed disabling instructions, see:
http://en.stealthsettings.com/disabl...osync-exe.html