Q:

Permissions to allow Dropbox access but prevent Anti-virus access

My computer has some anti-virus software installed that runs constantly and checks for what it believes are malicious executables.  I cannot disable or control the anti-virus software. 
I have dropbox installed and am trying to sync some executables that I know to not be malicious, but the anti-virus program believes they are. 
Shortly after Dropbox syncs the file to my computer the anti-virus software deletes it (puts in quarantine) and dropbox proceeds to remove it from all my other dropbox computers. 
I hoped I could modify permissions of the file to prevent this from happening.  I believe this comes down to determining which users both dropbox and the anti-virus run as (and the groups those users are in), and then configuring the appropriate permissions. 
I should also clarify that I am not trying to sync permissions across my machines, I am aware that doing that isn't possible yet. 
I've tried to determine which "user" the dropbox applications runs as.  Initially I thought it was my user, but when I removed permissions on the file for all expect my user dropbox notifies me that it "can't sync  access is denied". 
Is it possible to set the permissions of the file such that dropbox can access it but the anti-virus software cannot?  Has anyone accomplished something like this? 

A:

Most Antivirus (e.g. ESET, Norton, BitDefender, etc.)  will run as the System user (which will be able to access any file of any user).  In most cases the group Administrator (which I assume you are apart of) has less access than the group NT AUTHORITY (Which System is in).  To prevent the Antivirus from accessing your files you must also make them inaccessible to the operating system - which kind of defeats the purpose as dropbox will no longer have access to them. 
You will need to find what your Antivirus does not scan.  For example, some Antivirus do not scan removable media.  If you can find out if your Antivirus checks removeable media (most do not) automatically, you may be able to create a virtual USB drive to store the files (to prevent the Antivirus from scanning them, while also allowing Drop Box from accessing them).