Software Engineering Institute

Overview

The PCTCore64.sys Windows kernel driver from PC Tools Internet Security exposes its \\.\PCTCoreDriver device interface with no access control, allowing any user-mode process to interact with the driver and invoke privileged IOCTL (I/O Control) commands. In a Bring Your Own Vulnerable Driver (BYOVD) scenario, a local attacker with the ability to load a Windows driver can exploit the exposed interface to perform sensitive low-level operations on the target device.

Description

PCTCore64.sys is a Windows kernel driver that implements system monitoring and protection functionality on local Windows systems. The driver creates a Windows Driver Model (WDM) device object \\.\PCTCoreDriver via IoCreateDevice and provides user-mode access through a DOS device symbolic link via IoCreateSymbolicLink.

The driver exposes privileged functionality intended for administrative or security operations; however, the device object is created without a restrictive security descriptor. Specifically, the driver does not apply security best practices using either Security Descriptor Definition Language (SDDL) or the IoCreateDeviceSecure API, allowing unprivileged user-mode processes to open handles to the device and issue privileged IOCTL requests.

As a result, an attacker may invoke IOCTL handlers capable of performing sensitive low-level operations, including:

• System-wide handle enumeration
• Cross-process handle manipulation
• Credential extraction from lsass.exe
• Forced termination of arbitrary processes, including Protected Process Light (PPL)-protected processes

Although the original PC Tools Internet Security product line was discontinued in 2013 and is no longer maintained, the driver remains signed and can still be abused in BYOVD attacks. An attacker may load the vulnerable driver on a target system and leverage the exposed IOCTL interface to access privileged kernel functionality.

One vulnerable IOCTL permits the acquisition of a PROCESS_ALL_ACCESS handle to sensitive processes such as lsass.exe, enabling credential theft operations including extraction of NTLM hashes and Kerberos authentication material. Additional IOCTL handlers permit the termination of arbitrary processes regardless of PPL protections, enabling attackers to disable security software such as Microsoft Defender and other critical system services. Other exposed interfaces enable arbitrary handle operations against external processes, potentially resulting in process instability, crashes, or undefined behavior. Collectively, these vulnerabilities can be exploited to provide a practical attack path for credential theft, defense evasion, privilege escalation, and broader system compromise.

CVE-2026-8501 Improper access control in the PCTCore64.sys Windows kernel driver from PC Tools Internet Security allows user-mode processes to access the PCTCoreDriver WDM device interface and invoke privileged IOCTL handlers. A local attacker with the ability to access or load the affected driver can exploit this vulnerability to perform sensitive and privileged operations on the target system.

Impact

A local attacker with the ability to load a Windows kernel driver may exploit the vulnerable PCTCore64.sys driver to access sensitive processes such as lsass.exe and other PPL-protected services. Successful exploitation can enable credential theft, arbitrary process termination, denial-of-service (DoS) conditions, and broader system compromise through privileged kernel-level operations.

Solution

The PC Tools Internet Security product line and its PCTCore64.sys driver are no longer actively maintained and should not be used in production environments. Organizations should remove and block the vulnerable driver where possible and implement mitigations designed to reduce exposure to BYOVD attacks, including restricting administrative privileges, enforcing Microsoft recommended driver block rules, and enabling protections such as Hypervisor-Protected Code Integrity (HVCI), Windows Defender Application Control (WDAC), and Credential Guard.

Acknowledgements

Thanks to Tzachi Hazan for researching and reporting this vulnerability. This document was written by Molly Jaconski.

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