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
