8e6 Technologies R3000 Internet Filter Bypass by Request Split


Product:

8e6 Technologies R3000 Internet Filter
http://www.8e6.com/network-security/internet-filtering/internet-filtering.html


The HTTP URL filtering function provided by the 8e6 Technologies R3000 Internet Filter can be bypassed by simply splitting the HTTP request line (which contains the URI) into multiple packets.

Example:

packet 1: GE
packet 2: T / HTTP/1.0\r\n

This weakness is present regardless whether the site block is based on the DNS name or the IP address. For circumventing blocks based solely on the DNS name it is sufficient to arrange the HTTP request so that the request line and the Host header end up in separate packets.

Example:

packet 1: GET / HTTP/1.0
          X-SomeHeader: ...
          ....
          
packet 2: X-SomeOtherHeader: ....
          Host: www.blocked.com
          ...


The vulnerability has been identified in version 2.0.05.33. However, other versions may be also affected.


Solution:
Use a filtering solution that performs an HTTP request reassembly.


Found by:
nnposter