http://packetstormsecurity.org/files/111842/McAfee-Web-Gateway-And-Squid-Proxy-3.1.19-Bypass.html
# Exploit Title: Proxy URL Filtering Bypass
# Date: 13/04/2012# Author: Gabriel Menezes Nunes
# Version: McAfee Web Gateway and Squid Proxy
# Tested on: McAfee Web Gateway and Squid Proxy 3.1.19
# CVE: CVE-2012-2212 and CVE-2012-2213
I found a vulnerability in McAfee Web Gateway 7 and Squid Proxy that allows access to filtered sites.
The appliance/software believes in the Host field of HTTP Header using CONNECT method.
Example
CONNECT 66.220.147.44:443 HTTP/1.1
Host: www.facebook.com
It is blocked.
CONNECT 66.220.147.44:443 HTTP/1.1 (without host field)
It is blocked.
But:
CONNECT 66.220.147.44:443 HTTP/1.1
Host: www.uol.com.br (allowed url)
The connection works.
From here, I can send SSL traffic without a problem. This way, I can access any blocked site that allows SSL connections.
Others test that I did is convert GET methods in CONNECT methods.
GET http://www.facebook.com HTTP/1.1
Host: www.facebook.com
in
CONNECT 66.220.147.44:80 HTTP/1.1
Host: www.uol.com.br
It will connect.
and after it is possible to send the GET packets. It will work!
This vulnerability is different from the CONNECT Tunnel method. The flaw is on the Host field processing. The appliance believes on this field.
So, any sites can be accessed. URL filtering in this device/software is irrelevant and useless.
One of the most important (if not the most important) feature of this kind of device is to protect the network in accessing specific URLs. So, this flaw is very dangerous, and it can be implemented even in malwares, bypassing any protection.
I developed a python script that acts like a proxy and it uses this flaw to access any site.
This tool is just a proof of concept.
