Cache Poisoning DoS on updates.rockstargames.com

Summary

In this report, the researcher discovered that there was a cache poisoning weakness on updates.rockstargames.com due to an unkeyed header, trailer. By sending this header, an attacker could cause the cache to save a malformed response with status code 400.

An example of such a request, as provided by the researcher:

GET /patches/gtaiv/notes_title_update_6/GTAIVPC_TU6_Patch_Notes_FR.txt?donotpoisoneveryone=1 HTTP/1.1
Host: updates.rockstargames.com
trailer: 1

To resolve this issue, our team worked together with our CDN provider. The host no longer returns/saves a 400-code response when this header is sent in a request, and legitimate users can no longer be denied access to this content.

For more details about the vulnerability, check out: https://youst.in/posts/cache-poisoning-at-scale/