TPM chip vulnerabilities and risks without physical access

An independent researcher recently uncovered a critical vulnerability related to TPM chips, with the potential to expose stored data without the need for physical access to the system. This type of attack gives hackers the ability to decode protected information, such as information on drives encrypted with BitLocker. Microsoft, by requiring the presence and enabling of the TPM for the installation of Windows 11, has not slowed down the interest of the security community, which continues to try and find ways to compromise the protection offered by the TPM chips. In particular, an expert recently reported a problem to Intel, revealing technical details that allow you to bypass the protection without physically accessing the device components.

Outdated firmware issues and potential attacks

On Intel systems, discrete TPM chips are connected to the Platform Controller Hub (PCH) via buses such as LPC or eSPI. The PCH, designed to manage input/output between the processor and motherboard, also controls various hardware reset pins. Many of these pins can be configured for multiple uses via software, and the GPIO block allows control of the state of each pin. This is the weak point: by manipulating the GPIO pin, a hacker can simulate a hardware reset and restore the state of the TPM, resetting the values of the Platform Configuration Registers (PCR). This paves the way for serious compromises of cryptographic systems like BitLocker.

Incomplete implementation and missing firmware updates

Intel has proposed a mitigation via a PCH-level update that allows the firmware to lock the GPIO pin configuration. However, not all OEM manufacturers have implemented these measures correctly, making an additional firmware update necessary to effectively protect devices. Well-designed firmware should prevent any subsequent software from exploiting this vulnerability. Intel has included instructions for enabling these security measures in its BIOS developer guide, which is accessible only through a non-disclosure agreement (NDA). At the moment, however, there does not seem to have been any concrete evidence of devices in which these indications have been applied correctly.

Next steps and vulnerability detection software

The researcher who discovered the vulnerability has announced plans to soon release detection software that will allow users to see if their devices are at risk. This tool will be shared publicly, providing a useful tool for the IT community to identify and mitigate the issue. In the meantime, security experts recommend staying updated and considering additional protection measures for critical data, pending permanent fixes on the firmware side. The discovery highlights the importance of taking a proactive view on the security of hardware devices and ensuring timely and correctly implemented updates.