VU#282450: Out-of-Bounds read vulnerability in TCG TPM2.0 reference implementation

Overview

An out-of-bounds (OOB) read vulnerability has been identified in the Trusted Platform Module (TPM) 2.0 reference library specification, currently at Level 00, Revision 01.83 (March 2024). An attacker with access to a TPM command interface can exploit this vulnerability by sending specially crafted commands, potentially leading to unauthorized access to sensitive data or denial of service of the TPM.

Description

Trusted Platform Module (TPM) technology is a hardware-based solution that provides secure cryptographic functions to operating systems on modern computing platforms. Designed to resist tampering, TPM can be implemented as a discrete chip, integrated component, or firmware-based module. Software-based implementations are also available to support the cryptographic needs of cloud and virtualized environments. The Trusted Computing Group (TCG) maintains the TPM specifications and provides a reference implementation to assist vendor adoption.

A Security researcher have discovered an OOB read vulnerability in the CryptHmacSign function of the reference implementation. The issue arises because the reference code did not implement appropriate consistency checks in CryptHmacSign function resulting in potential out-of-bound read. An attacker with access to the TPM interface can exploit this mismatch by submitting a maliciously crafted packet, resulting in an out-of-bounds read from TPM memory, which may expose sensitive data.

Impact

An authenticated local attacker can send malicious commands to a vulnerable TPM interface, resulting in information disclosure or denial of service of the TPM. The impact assessment depends on the vendor specific implementation.

Solution

The TCG has released an errata update to the TPM 2.0 Library Specification and updated the reference implementations to address this vulnerability. Users are strongly encouraged to apply TPM-related firmware updates provided by their hardware or system vendors. Please refer to the Vendor Information section for any specific guidance from affected vendors. TPM2.0 vendors are urged to use the latest specifications and the reference implementation to ensure these vulnerabilities are resolved in their implementations. TCG has published VRT009 advisory and uses VRT0009 to track this advisory.

Acknowledgements

Thanks to the reporter, who wishes to remain anonymous. This document was written by Vijay Sarvepalli.