CVE-2007-4968 in Privatefirewall
Summary
by MITRE
Privatefirewall 5.0.14.2 does not properly validate certain parameters to System Service Descriptor Table (SSDT) function handlers, which allows local users to cause a denial of service (crash) and possibly gain privileges via kernel SSDT hooks for (1) NtOpenProcess and (2) NtOpenThread.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/08/2018
The vulnerability identified as CVE-2007-4968 affects Privatefirewall version 5.0.14.2 and represents a critical kernel-level flaw that undermines the security integrity of Windows operating systems. This issue stems from improper parameter validation within the System Service Descriptor Table (SSDT) function handlers, which are fundamental components of the Windows kernel responsible for managing system service calls. The vulnerability specifically targets two critical system functions: NtOpenProcess and NtOpenThread, which are essential for process and thread manipulation within the operating system. The flaw exists because the firewall software fails to adequately validate input parameters before processing them through kernel-level hooks, creating an exploitable condition that can be leveraged by local attackers.
The technical implementation of this vulnerability allows an attacker with local system access to manipulate the SSDT function handlers by injecting malicious parameters through the NtOpenProcess and NtOpenThread system calls. When these functions are invoked with malformed or unexpected parameters, the kernel's validation mechanisms fail to properly sanitize the inputs, leading to potential kernel memory corruption. This memory corruption can manifest as system crashes or blue screen errors, resulting in denial of service conditions that effectively render the affected system unusable. More critically, the improper validation creates opportunities for privilege escalation attacks where an attacker could potentially elevate their privileges from standard user level to kernel level access, bypassing the normal security boundaries that protect the operating system from unauthorized manipulation.
From an operational impact perspective, this vulnerability poses significant risks to enterprise environments where Privatefirewall is deployed, as local privilege escalation capabilities can enable attackers to gain complete system control. The vulnerability's exploitation requires only local access, making it particularly dangerous in environments where user accounts may have elevated privileges or where physical access to systems is possible. The denial of service component can be used for persistent disruption attacks, while the privilege escalation potential allows for long-term persistence and data exfiltration. This vulnerability directly maps to CWE-122, which describes improper validation of input parameters, and aligns with ATT&CK techniques related to privilege escalation and defense evasion through kernel manipulation.
Mitigation strategies for CVE-2007-4968 should prioritize immediate patching of the Privatefirewall software to the latest version that addresses the SSDT validation issues. Organizations should implement strict access controls to limit local user privileges and ensure that only trusted administrators have access to systems running this firewall software. Network segmentation and monitoring solutions should be deployed to detect anomalous system call patterns that might indicate exploitation attempts. Additionally, regular security assessments should verify that kernel-level hooks are properly configured and that no unauthorized modifications exist in the SSDT tables. System hardening measures including disabling unnecessary services and implementing kernel patch protection mechanisms can further reduce the attack surface. The vulnerability demonstrates the critical importance of proper input validation in kernel-level software components and highlights the need for comprehensive security testing of security tools to prevent them from becoming attack vectors rather than protective measures.