Outpost Bypassing Self-Protection using File Links Vulnerability
17 Jan. 2007
Summary
A vulnerability in Outpost allows attackers to bypass the self-protecting mechanism of the program allowing attackers to cause it to execute arbitrary code.
Vulnerable software:
* Outpost Firewall PRO 4.0 (1005.590.123)
* Outpost Firewall PRO 4.0 (971.584.079)
* Outpost Firewall PRO 4.0 (964.582.059)
* probably all older versions of Outpost Firewall PRO 4.0
* possibly older versions of Outpost Firewall PRO
Outpost protects its files and forbids other applications to manipulate them. Files and directories in its installation directory are guarded by various SSDT hooks. However, the implementation of this protection does not prevent malicious applications to call native API ZwSetInformationFile class FileLinkInformation. Such calls can be used to replace files that are not used by the system when this function is called. One of vulnerable files in the Outpost installation directory is SandBox.sys, the driver that implements Outpost Self-Protection mechanisms. Attackers are able to replace this driver with a fake copy that will be loaded into the system after the next reboot. This can result in a complete system control because driver's code is executed in the privileged kernel mode. The fake driver can be implemented such that the user has no chance to notice the attack.
