January 4th, 2005, 03:17 PM
Multiple Firewall Products Bypass Vulnerability
Most of personal firewalls allow shortcuts or interface for controlling traffic. It's simple to bypass these firewalls by a multithreaded program and sending keys or by contolling mouse.
This flaw enables that any Trojan or similar programs can easily bypass firewall and act as a server or access to another computer. Also most of these firewalls have a "remember" option so if you bypass firewall and successfully exploit it, firewall will never ask again.
This is a similar threat with shattering attacks, but different method and impact.
Vulnerable Products (Sending Key Method and Mouse Control);
These products are vulnerable to both of "Sending Key Method" and "Mouse Control Method"
Fully Patched Windows XP Professional and Windows 2003 Enterprise Edition (May 19, 2004 - 01.01.2005)
ZoneAlarm / ZoneAlarm Pro (www.zonelabs.com) | Fixed
4.5.530.000 - Tested
4.5.538.001 - Tested
5 and newer versions are not vulnerable...
4.0.14 - Tested
Agnitium Outpost Firewall (www.agnitium.com)
2.1.303.4009 (314) - Tested
2.5.369.4608 (369) - Tested
Kaspersky Anti-Hacker (www.kaspersky.com)
188.8.131.52 - Tested
Look 'n' Stop (www.looknstop.com)
2.04p2 - Tested
Symantec's Norton Personal Firewall (www.norton.com)
2004 - Tested
Vulnerable Products (Mouse Control);
These products are only vulnerable to "Mouse Control Method", because they don't accept shortcuts but still vulnerable to "Mouse Control" attacks.
Panda Platinum Internet Securiy
Omniquad Personal Firewall
Proof of Concept;
2 Proof of Concepts attached to advisory (also some other POCs for some firewalls)
First POC (bypassSendKey.vbs) written in VBScript (.vbs), This POC include required samples for ZoneAlarm, Kerio, Agnitium, Kaspersky Anti-Hacker, Look 'n' Stop and Symantec's Norton Personal Firewall. This script is executing an instance of itself for multithreading and send shortcuts to firewall while first instance trying to connect internet. I didn't write an auto determine firewall function (but it's so easy), so you need to set it by yourself.
Second (bypassMouseControl.txt) simulates an example of bypassing Zone Alarm Firewall by with mouse control, code in VB.NET. Program is not using a real multithread because some firewalls interrupt executing of program directly. So program is executing another instance of itself with an argument.
Both of them add themselves to secure app list of firewalls and then bypass active firewall.
Also I attached testFirewall.vbs for testing your firewall for application control.
All firewalls should ask password for all kind of "Allow" actions. In fact passwords can be fooled because of its nature but it is the best user friendly / secure solution for protection.
As a user of these firewalls, if your firewall supports to "deny all default" option, enable it, so your firewall deny all connections by default. After that you may can manually select programs for allow them.
This is a methodology for bypassing interacted firewalls so it's possible that this advisory affects other firewalls in market. Also it's possible that future firewalls will be affected too. I think for now this is a serious problem for firewalls, until they imply password/random human need text method for "Allow/Deny" actions.
Vendors Informed: 28.08.2004
Special thanks to ZoneLabs Team.
Web Application Security Specialist