Forbidden error when trying to post

[Kelley]

All of a sudden our forum started generating this error message when trying to post a new thread:

Forbidden
You don't have permission to access /forums/newthread.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Searching here and via Google, I found a Machol and Zachary post regarding ModSecurity here. http://www.vbulletin.com/go/modsecurity However, this did not solve the issue. I've upgraded to the latest version this evening, still same issue. Checked groups, group permissions, etc, everything in the AdminCP looks unchanged, as it should be.

I've seen some threads indicating this is somehow a security related issue, perhaps modsecurity and htaccess related, so I'm working with my host on this issue as well, so I'd like to pass any guidance along to them since they're also looking into it.

Is there anyone else here who has recently experienced this problem, and if so, what was the fix?

Thanks in advance.

[Kelley]

I'm not sure if this helps me troubleshoot, I see this entry in the server log after getting the forbidden error.

[Sun Nov 24 08:10:16 2013] [error] [client xxx.xxx.xxx.xxx] File does not exist: /home/power/public_html/403.shtml, referer: http://www.myforums.com/forums/newthread.php?do=newthread&f=4

There are also an enormous amount of errors indicating "client denied by server configuration:" . . . .

[Lynne]

This is a server configuration problem. You need to talk to your host about this.

[Kelley]

Thanks Lynne. I've been working with my host on this issue as well, and they are trying to help me resolve the problem. I provided the link to Zachary and Machol's post from a few years ago, but other than that post, even Google only shows people complaining about the problem, but nobody providing specifics on how to fix the issue.

So is there any other detail you can give me, or some hints on areas my host should be looking into?

Thanks in advance.

[Wayne Luke]

Most likely reason is a word is being denied in the post request via Suhosin or mod_security. Common words would be select, delete, get, new, update. Could be they have the server to access 10 variables per form and we're sending more than that. You're hosting provider should have access to the error and server logs and should be able to determine the exact cause though.

[Kelley]

Wayne, I love you man!! This is the sort of detail that will help my host provider find out why we're getting this error page when trying to post a message. Thank you.

I just sent them a copy of the post I'm trying to make, it's related to my club offering new sweatshirts for sale. So something in the message text may be flagging the post and I get the forbidden page. I get no errors posting other messages, example a "Test Post" title with "this is a test message" goes through without a problem.

If and when we find the fix, I'll stop back to post a follow up message here for future reference. One of my pet peeves is users who post messages here in the forums, and then never follow up with the fix in their thread.