Kerio Personal Firewall's Application Launch Protection Can Be Disabled by Direct Service Table Restoration

["Jérôme" ATHIAS <jerome.athias () caramail com>]

by Tan Chew Keong
Release Date: 02 Sep 2004 
Summary

Kerio Personal Firewall 4 (KPF4) is a state-of-the-art personal firewall that helps users restrict how their computers 
exchange data with other computers on the Internet or local network. KPF has an Application Security feature that 
allows the user to restrict the execution of programs on his system. KPF prevents malicious code from spawning 
processes on the user's system by prompting the user for action whenever an unknown/new or modified program is being 
executed. 

KPF's Application Security feature is implemented by hooking several native APIs in kernel-space by modifying entries 
within the SDT ServiceTable. This means that a malicious program can disable this security feature by restoring the 
running kernel's SDT ServiceTable with direct writes to \device\physicalmemory. This vulnerability affects only the 
execution protection feature of KPF4, the firewall feature of KPF4 remains intact. 

 
Tested System

Kerio Personal Firewall 4.0.16 on Win2K SP4, WinXP SP1,SP2.


 
Details

Kerio Personal Firewall's Application Security (execution protection) feature is implemented by hooking several native 
APIs in kernel-space. Hooking is performed by the module fwdrv.sys by replacing entries within the SDT ServiceTable. 
KPF prevents malicious code from spawning processes on the user's system by prompting the user for action whenever an 
unknown/new or modified program is being executed. 

More Details:

http://www.security.org.sg/vuln/kerio4016.html