CVE-2023-22745 is a classic buffer overflow vulnerability (CWE-120) identified in the tpm2-tss open source software stack, which implements the Trusted Platform Module (TPM) 2.0 software interface. The vulnerability exists in the functions Tss2_RC_SetHandler and Tss2_RC_Decode, which handle response code layers by indexing into the layer_handler array using an 8-bit layer number. However, the array size is limited to TPM2_ERROR_TSS2_RC_LAYER_COUNT entries, and when a layer number exceeds this count, the code reads or writes beyond the array boundary, causing a buffer overrun. This memory corruption can lead to arbitrary code execution if exploited. An example attack vector includes a man-in-the-middle (MiTM) bus attack that returns a crafted response code such as 0xFFFFFFFF, triggering the overflow. Exploitation requires local system privileges with administrative rights to access the TPM interface, which is typically restricted. The vulnerability affects tpm2-tss versions prior to 4.1.0-rc0, 4.0.1, and 3.2.2-rc1, all of which contain patches to prevent this out-of-bounds access. The CVSS v3.1 score is 6.4 (medium severity), reflecting the need for high privileges and the complexity of exploitation. No known exploits have been reported in the wild to date. Given the widespread use of TPM modules for hardware-based security functions such as secure boot, disk encryption, and platform integrity verification, this vulnerability poses a significant risk if left unpatched, especially in environments where attackers can gain local administrative access.

For European organizations, the impact of CVE-2023-22745 can be significant due to the reliance on TPM modules for securing sensitive operations including cryptographic key storage, device attestation, and secure boot processes. Successful exploitation could allow an attacker with local administrative access to execute arbitrary code within the TPM software stack context, potentially compromising the integrity and confidentiality of cryptographic operations and sensitive data. This could lead to unauthorized access to encrypted data, bypassing of platform security controls, and persistence mechanisms that evade detection. Critical sectors such as finance, government, healthcare, and critical infrastructure, which often mandate TPM usage for compliance and security, are particularly at risk. The requirement for local administrative privileges limits remote exploitation but does not eliminate risk from insider threats, compromised endpoints, or attackers who gain physical or remote administrative access through other means. The vulnerability could also undermine trust in hardware-based security assurances, impacting supply chain security and regulatory compliance across the EU.

To mitigate CVE-2023-22745, European organizations should: 1) Immediately upgrade tpm2-tss to versions 4.1.0-rc0, 4.0.1, 3.2.2-rc1 or later where the vulnerability is patched. 2) Restrict local administrative access to systems with TPM modules, enforcing strict access controls and monitoring for unauthorized privilege escalation. 3) Implement endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts targeting TPM interfaces. 4) Harden physical and logical security controls to prevent unauthorized local access, including secure boot and BIOS/UEFI password protections. 5) Regularly audit TPM usage and software stack versions across the enterprise to ensure compliance with security policies. 6) Educate system administrators and security teams about the risks associated with TPM vulnerabilities and the importance of timely patching. 7) Consider network segmentation and isolation of critical systems to limit lateral movement if local compromise occurs. These steps go beyond generic advice by focusing on the unique access requirements and security context of TPM components.