I tried to send the bad curl request to our servers (test env, obviously) and I didn't get any error. It seems I should be getting "Requested Range Not Satisfiable" if the server is vulnerable and "The request has an invalid header name" if it's patched. I'm getting neither, simply a normal response HTTP 200 with the requested page. Anyone knows how to really test it?
EDIT : It is indeed related to "Output Cache" setting in IIS as I said I was suspecting in another comment. I managed to crash our servers by going to IIS Management, select the website I wanted to test, go to Output Caching, enable the feature AND also add a rule (I added a rule for .png just to test). If you have NO rules it is the same as having the feature disabled so you are safe. If you add a rule and check "Enable Kernal Caching" you are vulnerable!
EDIT 2 : As some have asked, this is the command I used to crash our test server. I tested it after having created a new Output Caching rule to cache all .png files in kernel mode.
curl -v http://example.com/image.png -H "Range: bytes=18-18446744073709551615"
I didn't take a screenshot of the BSOD and I don't plan on crashing our test env a second time today because people are using it (I tested it early enough that not a lot of people were at the office yet).
EDIT : It is indeed related to "Output Cache" setting in IIS as I said I was suspecting in another comment. I managed to crash our servers by going to IIS Management, select the website I wanted to test, go to Output Caching, enable the feature AND also add a rule (I added a rule for .png just to test). If you have NO rules it is the same as having the feature disabled so you are safe. If you add a rule and check "Enable Kernal Caching" you are vulnerable!
EDIT 2 : As some have asked, this is the command I used to crash our test server. I tested it after having created a new Output Caching rule to cache all .png files in kernel mode.
curl -v http://example.com/image.png -H "Range: bytes=18-18446744073709551615"
I didn't take a screenshot of the BSOD and I don't plan on crashing our test env a second time today because people are using it (I tested it early enough that not a lot of people were at the office yet).