>>>>If they can compromise your site (eg. upload a file and get it executed)
>>
>>OK so the security concern is to prevent the amount of damage that can be done after the system has already been compromised. There isn't just some easy way for IUSR to upload or modify a file just because it has write/modify privileges.
>>
>
>Basically the idea is to minimize the surface area that a hacker can attack. You usually only want to give the very minimum amount of permissions required to get things to work.
>
>>One fundamental thing I guess I don't get. Once they manage to get an executable uploaded. Wouldn't it execute under the ASPNET/NETWORK account?
>>
>
>Only if it's an ASPX page (eg. a page run under ASP.NET, and not something else, eg. classic ASP). There are also attacks which don't really target the website but use the website to infect other machines.

Thanks, that helped a lot. First clear explanation of the dangers I've seen. It's a lot easier to evaluate what you are doing when you understand it. <g>

I changed hosts and stuff is now working correctly, so I don't have to worry about monkeying around with the IUSR permissions anymore. But this will help me understand the issue when it comes up in the future.