Php – How to enable HTTP POST requests in IIS7

With Failed Request Tracing, you need to setup the rule, but as a separate step you must turn it on. In the Failed Request Tracing, check the Action pane on the right, that will have an option to enable it. That's my guess as to why the tracing isn't working.

My recommendation on any configuration in IIS7 where you have 1 site per app pool, or when all sites trust each other and the sites are stable, is to set Anonymous authentication to use the identity of the app pool. That gives you one less user to deal with. Then make sure that the app pool identity is granted permission on disk.

You mention that it doesn't work in the subfolder. It is possible to have different permissions or a different app pool used for a sub-application. Double check the app pool being used, and anonymous auth settings.

Finally, use Process Monitor as Colin suggested. Get it from www.sysinternals.com. It's free, safe to run on a production server and you'll figure it out in under 10 minutes. That will tell you exactly which user is denied access to which folder (or registry key).

First of all, you should know that you are running an obsolete version of ModSecurity (branch 1.x). If you are running Apache 2.0.x you should upgrade to ModSecurity 2.x. If you are still running Apache 1.3.x then I am afraid that you don't have a choice since ModSecurity 2.x won't work with it. ModSecurity 1.x itself is not known to be vulnerable, but its rule engine is too inflexible for today's demands.

If I recall correctly, ModSecurity 1.x required POST requests to specify content length purely because it didn't support chunked request bodies (the alternative way of submitting request bodies, in which the total length is not known until the end). Chunked request bodies were incredibly rare then (we're talking years 2003, 2004) and are still rare (although some mobile devices are using them).

There are no such restrictions in ModSecurity 2.x.

If you remove that rule you will create a big hole through which someone could sneak in an attack undetected. On the other hand, I can argue that, with you running ModSecurity 1.x, there are other ways to do the same. Alternatively, tweak the rule to refuse requests that have the Transfer-Encoding request header set. You should be safe with that.

Disclosure: I wrote ModSecurity.