Question

I am running IIS 7 and ASP.NET 4. It’s an online charting application where one folder needs to have read/write access. Users don’t upload anything into this folder directly; instead they configure chart settings and then ASP.NET generates the chart on the server and saves it as an image into that read/write folder. Users are redirected to download the image of the chart from that folder.

In order to allow IIS/ASP.NET to save an image into the folder, I give WRITE permission to IIS AppPool/ChartApp account.

But, I am worried to have write access on a folder that’s open to HTTP. While there is no direct way to upload a file via my site into that folder, I am concerned that hackers will find a way to upload a script and then execute it. Are these valid concerns? Is there anything else I need to do to secure such a read/write folder?

Thanks.

Answer 1

What I ended up doing is to use a different account to write the file. The code from this article worked well for impersionation. The account that writes the file has write permissions, and the “main” AppPool account is still read only.