CVE-2023-33037 in 8 Gen 1 Mobile Platform
Summary
by MITRE • 01/02/2024
Cryptographic issue in Automotive while unwrapping the key secs2d and verifying with RPMB data.
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Analysis
by VulDB Data Team • 08/17/2026
The identified vulnerability represents a critical failure in the cryptographic integrity verification mechanisms within automotive embedded systems, specifically concerning the handling of wrapped keys during interaction with the Replay Protected Memory Block (RPMB) interface. In modern vehicle architectures, secure boot processes and trusted execution environments rely heavily on hardware-backed security modules to store sensitive credentials such as encryption keys used for securing communication buses like CAN FD or Ethernet-based intraventricular networks. The RPMB is a dedicated partition within eMMC storage devices that provides authenticated write access and replay protection, ensuring that only authorized entities can modify critical data and preventing attackers from reverting the system state to a previous version where vulnerabilities might have existed. When an automotive component attempts to unwrap a key stored in this secure environment using the secs2d protocol or similar cryptographic primitives, it must verify that the unwrapped material matches expected values derived from RPMB metadata to ensure authenticity and integrity.
The core technical flaw lies in the verification logic employed during the unwrapping process. Instead of performing a strict comparison between the decrypted key material and the reference data stored securely within the RPMB partition, the implementation likely suffers from improper error handling or incomplete validation checks. This could manifest as accepting partial matches, ignoring hash mismatches due to early termination conditions in the verification loop, or failing to validate the authenticity tag associated with the wrapped key before proceeding with its usage. Such a lapse allows an attacker who has gained physical access to the vehicle's diagnostic port or network interface to manipulate the RPMB data or intercept and alter cryptographic operations. By exploiting this weakness, it is possible to inject malicious keys into the system without triggering the expected integrity failure mechanisms, effectively bypassing the security boundary established by the hardware root of trust.
From an operational perspective, this vulnerability poses a severe risk to vehicle safety and privacy. If an attacker successfully substitutes or modifies cryptographic keys through this flaw, they can decrypt sensitive telemetry data, manipulate control messages on internal networks, or even disable critical safety features that rely on authenticated communication channels. For instance, in electric vehicles where battery management systems communicate with charging stations using encrypted protocols, compromised keys could allow for malicious commands to be issued, potentially leading to thermal runaway conditions or unauthorized energy theft. Furthermore, the ability to bypass RPMB verification undermines the entire chain of trust established during manufacturing and provisioning phases, rendering other security controls such as secure boot signatures ineffective if the underlying cryptographic material is no longer trusted by the system.
This issue aligns closely with CWE-327, which describes the use of a broken or risky cryptographic algorithm, although in this context it extends to improper implementation of cryptographic functions rather than just weak algorithms like DES or MD5. It also relates to CWE-345 regarding insufficient verification of data authenticity and integrity. In terms of offensive security frameworks such as MITRE ATT&CK for ICS, this vulnerability facilitates techniques associated with Defense Evasion by allowing attackers to bypass authentication mechanisms and potentially Data Injection via manipulation of stored credentials. The exploitation path typically involves gaining initial access through physical interfaces like OBD-II ports or wireless entry points followed by privilege escalation within the embedded OS to interact directly with storage controllers.
Mitigation strategies must focus on hardening the cryptographic verification routines within the secure element or microcontroller firmware responsible for RPMB interactions. Developers should implement strict, constant-time comparison functions when validating unwrapped keys against reference data stored in RPMB to prevent timing side-channel attacks and ensure that any discrepancy results in an immediate abort of the operation rather than partial acceptance. Additionally, integrating hardware-based attestation mechanisms can help verify that the software executing the unwrap routine has not been tampered with before allowing access to sensitive key material. Regular security audits focusing on cryptographic implementation details are essential, along with adhering to standards such as ISO/SAE 21434 for road vehicles cybersecurity engineering which emphasizes threat analysis and risk assessment throughout the vehicle lifecycle. Updating firmware patches that address these specific validation flaws is critical to restoring trust in the automotive supply chain's security posture.