Security researchers Per Idenfeldt Okuyama and Sam Eizad have uncovered a critical physical attack vulnerability in the Moxa UC-1222A Secure Edition industrial computer, demonstrating that its LUKS full-disk encryption can be fully defeated by passively sniffing the SPI bus between the processor and the discrete TPM 2.0 chip during system boot.
The flaw, tracked as CVE-2026-0714, represents the first publicly documented TPM sniffing attack where the TPM2_NV_Read command rather than the more commonly observed TPM2_Unseal is the mechanism releasing the disk decryption key.
| CVE ID | Affected Product | Platform | Attack Vector | Severity |
|---|---|---|---|---|
| CVE-2026-0714 | Moxa UC-1222A Secure Edition | Moxa Industrial Linux 3 | Physical (SPI Bus) | High |
How the Attack Works
The Moxa UC-1222A is an ARM-based industrial computer marketed as a hardened platform for embedded data acquisition and field-site deployments, designed with Trusted Platform Module (TPM 2.0) backed LUKS encryption.
During boot, the device’s SoC issues a TPM2_NV_Read command to retrieve the LUKS disk decryption key from the TPM’s protected non-volatile index.
Although the TPM correctly enforces the PCR-bound authorisation policy, the returned key material is transmitted in plaintext over the SPI bus without any cryptographic session protection, allowing a physically positioned attacker to intercept the full key.
Researchers Per Idenfeldt Okuyama and Sam Eizad of CYLOQ assessed in October 2025 using a Saleae Logic 8 eight-channel logic analyser connected directly to the four SPI pins of the Infineon SLB9670 TPM 2.0 chip CS#, MISO, MOSI, and SCLK.
The analyzer was configured at 250 MS/s to record the entire ~50-second boot sequence. Custom Python scripts parsed the exported SPI traffic CSV, located the TPM_CC_NV_Read command code (0x0000014E) in the MOSI stream, and carved the plaintext LUKS key from the corresponding MISO response.
The researchers subsequently validated the recovered key by de-soldering the device’s eMMC flash chip, dumping its contents using an Allsocket eMMC153 reader, and successfully mounting the encrypted partition using the sniffed passphrase.
A notable distinction from prior BitLocker-focused attacks is that this exploit targets a Linux ICS environment using a custom vendor initramfs hook rather than Clevis or any standard framework, highlighting that vendor-specific provisioning logic can introduce the same class of vulnerability.
Moxa acknowledged the issue and published a security advisory on February 5, 2026.
The Trusted Computing Group’s CPU-TPM Bus Protection Guidance recommends mitigating this attack class through TPM parameter encryption, which encrypts sensitive command and response parameters within authorised sessions, ensuring that key material is never exposed in plaintext over the SPI bus.
CYLOQ has also released an open-source Saleae plugin on GitHub for automated extraction of NV_Read secrets, raising awareness of how straightforward the interception can be against devices with an unprotected discrete TPM.
Organizations operating Moxa UC-1222A Secure Edition devices in environments where physical access cannot be strictly controlled should treat this vulnerability as a high-priority risk, particularly in unmonitored remote or field-deployed industrial settings where an adversary could have extended access to the hardware.
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