ForeFront Error for Excel - Large Uncompressed File

We have begun to use SSRS in our environment. I am huge fan of what it can do, even though I don't know that much about it. One thing that it did allow our users to do is to download raw data. This is great, because now they have access to it. However, an issue recently arose when a user wanted to share that data on SharePoint with Forefront installed.

Recently, a user exported raw data from the SSRS into an Excel 2007 spreadsheet. He wanted to share that data with his team, so tried to upload it to a SharePoint library. It failed with the following error: Virus Name - "Large Uncompressed Size".

The file was not too large - only 33 MG. (Ok, that does sound large. But our upload limit is 150 MG, so it should not have had a problem.) During troubleshooting, I converted the file to a 2003 Excel file and it inflated the size to 88 MG, but it uploaded fine. It also uploaded fine in comma delimited text format. Additionally, I cut out half the data (down to 22,000 rows) and it uploaded okay. Just for fun, I created another worksheet in the same workbook and pasted the 23,000 rows I had cut from the first worksheet. It also uploaded just fine. Therefore, the problem was not the data and of course there was no actual virus.

Although we did not realize it until we had spent days testing, part of the issue actually had to do with the amount of rows and columns that the spreadsheet contained in a single worksheet - 45,000 rows and 250+ columns. The other part had do do with the XML structure of Excel 2007 documents. Forefront was actually timing out when it tried to read all of that XML data in one chunk. This is why dividing it up the data into smaller chunks allowed the document to upload successfully.

When we contacted Microsoft for problem resolution, they suggested that we turn off scanning for all Excel files. We informed them (very nicely) that this was against our security protocol. After a few days, they came back with a fix that involved adding two registry keys specific to Excel files that would increase the timeout limit on scanned Excel documents.

I have good and bad news. The good news is that this worked. The bad news is that due to Microsoft legalities with my company, I was not allowed to publish the registry keys that needed to be added. Apparently, this is "super confidential" and my network administrator did not feel comfortable letting me in on the secret. That said, I wanted to post this anyway in order to give anyone out there the comfort that there is actually a fix for this annoying problem.

By the way, there are a few Microsoft KB Articles out there that reference altering registry keys for a similar issues. Keep in mind these do not work for this particular Excel issue, but it is worth noting here:

http://support.microsoft.com/kb/972074 -Refers to the errors you recieve when you upload a document that contains smaller files that exceed the Forefront upload limit. It also mentions how to skip the scanning of these documents.

http://support.microsoft.com/kb/972072/ - Walks you through the process of eliminating large uncompressed files from the ForeFront scan.