ARM Trusted Platform

Version: 1.0

Authors: David Cervigni

Executive Summary

This section contains an executive summary of the identified threats and their mitigation status

There are 10 unmitigated threats without proposed operational controls.

Threats Summary

This section contains an executive summary of the threats and their mitigation status

There are a total of 10 identified threats of which 10 are not fully mitigated by default, and 10 are unmitigated without proposed operational controls.

Threat IDCVSSValid when (condition)Fully mitigatedHas Operational
countermeasures
Trusted_Firmware.
MALICIOUS_FIRMWARE_UPDATE 		8.6 (High) Always valid ❌ No
Trusted_Firmware.
SECURE_STORAGE_COMPROMISE 		8.1 (High) Always valid ❌ No
ARM_TrustedPlatform.
MALICIOUS_KERNEL_ACCESS 		7.6 (High) Always valid ❌ No
Trusted_Firmware.
BOOTLOADER_ATTACK 		7.6 (High) Always valid ❌ No
Trusted_Firmware.
SUPPLY_CHAIN_INJECTION 		7.0 (High) Always valid ❌ No
ARM_TrustedPlatform.
SIDE_CHANNEL_ATTACK 		6.4 (Medium) Always valid ❌ No
ARM_TrustedPlatform.
FIRMWARE_EXPLOIT 		6.4 (Medium) Always valid ❌ No
ARM_TrustedPlatform.
ROGUE_DEVICE_ACCESS 		6.4 (Medium) Always valid ❌ No
ARM_TrustedPlatform.
SECURE_BOOT_SPOOFING 		6.4 (Medium) Always valid ❌ No
Trusted_Firmware.
RUNTIME_MEMORY_ATTACK 		6.4 (Medium) Always valid ❌ No

ARM Trusted Platform - scope of analysis

Overview

NOTE: this is an example is a threat model created by training an LLM

This document outlines potential threats to the ARM Trusted Platform, focusing on threats to trusted execution environments (TEEs), secure boot mechanisms, and the integrity of platform firmware. Countermeasures are included to mitigate these threats.

ARM Trusted Platform security objectives

Data Security:

System Integrity:

Boot Integrity:

Trust Assurance:

Diagram: Details:

Platform Trust (PLATFORM_TRUST)

Maintain trust in the ARM hardware root of trust and secure firmware updates.

Priority: High

Attack tree:

Secure Boot Integrity (SECURE_BOOT)

Ensure the integrity and authenticity of firmware and boot loaders to prevent unauthorized code execution.

Priority: High

Attack tree:

Trusted Execution Environment Confidentiality (TEE_CONFIDENTIALITY)

Ensure that data and code within ARM TEEs remain confidential and inaccessible to unauthorized entities.

Priority: High

Attack tree:

Trusted Execution Environment Integrity (TEE_INTEGRITY)

Ensure the integrity of data, execution, and communication within ARM TEEs.

Priority: High

Attack tree:

Linked threat Models

  • Trusted Firmware (ID: ARM_TrustedPlatform.Trusted_Firmware)

ARM Trusted Platform Threat Actors

Actors, agents, users and attackers may be used as synonymous.

A malicious or compromised kernel attempting to in[...] (MALICIOUS_KERNEL)
Description:

A malicious or compromised kernel attempting to interfere with ARM TEE operations.

In Scope as threat actor:

Yes

Attackers targeting the ARM hardware, secure eleme[...] (HARDWARE_ATTACKERS)
Description:

Attackers targeting the ARM hardware, secure elements, or firmware to bypass protections.

In Scope as threat actor:

Yes

Attackers leveraging side-channel analysis to infe[...] (SIDE_CHANNEL_ACTORS)
Description:

Attackers leveraging side-channel analysis to infer sensitive information.

In Scope as threat actor:

Yes

Assumptions

PRIVILEGED_ATTACKER

Attackers may have privileged access (e.g., kernel-level or hypervisor control) and may attempt to subvert trusted components.

SIDE_CHANNEL_RISK

Side-channel attacks exploiting timing, power, or electromagnetic leakage are considered potential threats.

ARM Trusted Platform Attack tree

ARM Trusted Platform Threats

Note This section contains the threat and mitigations identified during the analysis phase.

Side-Channel Attacks on TEE (SIDE_CHANNEL_ATTACK)

Threat actors:
Threat Description

Attackers exploit physical or timing-based side channels, such as cache behavior, power consumption, or electromagnetic signals, to infer data processed within the TEE.

Impact

Leakage of sensitive information, such as cryptographic keys or private data, through side-channel analysis.
TEE_CONFIDENTIALITY

CVSS
Base score: 6.4 (Medium)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Counter-measures for SIDE_CHANNEL_ATTACK

CONSTANT_TIME_ALGORITHMS Use Constant-Time Algorithms

Implement constant-time cryptographic and critical operations to eliminate timing-based side-channel vulnerabilities.

Countermeasure in place? ❌ Public and disclosable? ✔

Kernel-Level Attacks on TEE (MALICIOUS_KERNEL_ACCESS)

Threat actors:
Threat Description

A compromised or malicious kernel attempts to read, write, or manipulate memory assigned to the TEE, breaking its isolation guarantees.

Impact

Exploitation of kernel-level privileges to interfere with or compromise the ARM TEE.
TEE_INTEGRITY

CVSS
Environmental score: 7.6 (High)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Counter-measures for MALICIOUS_KERNEL_ACCESS

MEMORY_ISOLATION Enforce Strong Memory Isolation

Utilize ARM's memory management unit (MMU) and hardware-based isolation mechanisms to prevent unauthorized kernel access to TEE memory.

Countermeasure in place? ✔ Public and disclosable? ✔

Exploitation of Insecure Firmware (FIRMWARE_EXPLOIT)

Threat actors:
Threat Description

Attackers inject malicious firmware or exploit bugs in existing firmware to gain control over secure operations, potentially bypassing the TEE or secure boot.

Impact

Execution of unauthorized or malicious code by exploiting vulnerabilities in platform firmware.
SECURE_BOOT

CVSS
Base score: 6.4 (Medium)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Counter-measures for FIRMWARE_EXPLOIT

FIRMWARE_VERIFICATION Verify Firmware Signatures

Enforce cryptographic signature validation during firmware updates and secure boot processes.

Countermeasure in place? ✔ Public and disclosable? ✔

Rogue Peripheral Attacks (ROGUE_DEVICE_ACCESS)

Threat actors:
Threat Description

Malicious devices connected to the platform exploit DMA (Direct Memory Access) or other interfaces to manipulate or extract data from the TEE.

Impact

Compromise of TEE operations through unauthorized access or manipulation by malicious peripherals.
TEE_INTEGRITY
TEE_CONFIDENTIALITY

CVSS
Base score: 6.4 (Medium)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Counter-measures for ROGUE_DEVICE_ACCESS

DMA_PROTECTION Restrict DMA Access

Implement IOMMU (Input-Output Memory Management Unit) to limit peripheral access to memory regions used by the TEE.

Countermeasure in place? ❌ Public and disclosable? ✔

Spoofing Secure Boot (SECURE_BOOT_SPOOFING)

Threat actors:
Threat Description

Attackers intercept or modify the boot process to execute unverified firmware or boot loaders, compromising the root of trust.

Impact

Undermining trust in the secure boot process by executing malicious code under the guise of legitimate firmware.
SECURE_BOOT
PLATFORM_TRUST

CVSS
Base score: 6.4 (Medium)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Counter-measures for SECURE_BOOT_SPOOFING

ROOT_OF_TRUST Use Hardware Root of Trust

Ensure the secure boot process is anchored to an immutable hardware root of trust to verify all stages of the boot chain.

Countermeasure in place? ✔ Public and disclosable? ✔

Trusted Firmware

Version: 1.0

Authors: David Cervigni

Trusted Firmware - scope of analysis

Overview

This document extends the ARM Trusted Platform threat model to focus specifically on threats to Trusted Firmware-A (TF-A). It addresses issues such as firmware integrity, secure storage, and runtime attacks, leveraging details from the Trusted Firmware-A documentation.

Trusted Firmware security objectives

System Integrity:

Runtime Security:

Data Security:

Update Security:

Diagram: Details:

Firmware Integrity (FIRMWARE_INTEGRITY)

Ensure that firmware is not tampered with during development, deployment, or runtime.

Priority: High

Attack tree:

Runtime Resilience (RUNTIME_RESILIENCE)

Protect the Trusted Firmware during execution, ensuring it cannot be subverted by runtime attacks.

Priority: High

Attack tree:

Secure Firmware Updates (FIRMWARE_UPDATES)

Ensure that firmware updates are authenticated and authorized to prevent malicious firmware from being executed.

Priority: High

Attack tree:

Secure Storage (SECURE_STORAGE)

Protect sensitive data stored by the Trusted Firmware, ensuring confidentiality and integrity.

Priority: High

Attack tree:

Trusted Firmware Threat Actors

Actors, agents, users and attackers may be used as synonymous.

Attackers inserting or modifying firmware to execu[...] (MALICIOUS_FIRMWARE)
Description:

Attackers inserting or modifying firmware to execute malicious actions.

In Scope as threat actor:

Yes

Attackers exploiting runtime vulnerabilities in Tr[...] (RUNTIME_EXPLOITERS)
Description:

Attackers exploiting runtime vulnerabilities in Trusted Firmware.

In Scope as threat actor:

Yes

Attackers compromising firmware integrity during t[...] (SUPPLY_CHAIN_ATTACKERS)
Description:

Attackers compromising firmware integrity during the development or distribution phases.

In Scope as threat actor:

Yes

Assumptions

PLATFORM_INTEGRITY_RISK

The platform may be exposed to physical or logical attacks targeting the integrity of firmware components.

PRIVILEGED_ATTACKERS

Privileged attackers (e.g., with kernel-level control) may attempt to compromise firmware operations.

Trusted Firmware Attack tree

Trusted Firmware Threats

Note This section contains the threat and mitigations identified during the analysis phase.

Unauthorized Firmware Updates (MALICIOUS_FIRMWARE_UPDATE)

Threat actors:
Threat Description

Attackers distribute unauthorized firmware updates by bypassing signature validation or exploiting insecure update mechanisms.

Impact

Execution of unauthorized or malicious firmware due to unverified updates, potentially compromising system integrity.
FIRMWARE_UPDATES

CVSS
Environmental score: 8.6 (High)
Vector:CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Counter-measures for MALICIOUS_FIRMWARE_UPDATE

UPDATE_SIGNING Enforce Update Signing

Require all firmware updates to be signed with a trusted cryptographic key before installation.

Countermeasure in place? ✔ Public and disclosable? ✔

Runtime Memory Manipulation (RUNTIME_MEMORY_ATTACK)

Threat actors:
Threat Description

Attackers use buffer overflows, heap spraying, or other techniques to manipulate memory used by Trusted Firmware.

Impact

Exploitation of vulnerabilities in Trusted Firmware's runtime memory, allowing attackers to inject malicious code or extract sensitive data.
RUNTIME_RESILIENCE

CVSS
Base score: 6.4 (Medium)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Counter-measures for RUNTIME_MEMORY_ATTACK

MEMORY_PROTECTION_UNITS Use Memory Protection Units (MPUs)

Leverage MPUs to enforce strict memory access policies, preventing unauthorized access or modification of firmware memory.

Countermeasure in place? ✔ Public and disclosable? ✔

Supply Chain Injection (SUPPLY_CHAIN_INJECTION)

Threat actors:
Threat Description

Attackers inject malicious code into firmware during development, testing, or distribution, exploiting weak supply chain controls.

Impact

Introduction of malicious firmware into the supply chain, compromising the integrity of devices using the firmware.
FIRMWARE_INTEGRITY

CVSS
Environmental score: 7.0 (High)
Vector:CVSS:3.1/AV:P/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Counter-measures for SUPPLY_CHAIN_INJECTION

SUPPLY_CHAIN_AUDITS Conduct Supply Chain Audits

Regularly audit firmware development and distribution processes to detect and mitigate supply chain risks.

Countermeasure in place? ❌ Public and disclosable? ✔

Secure Storage Breach (SECURE_STORAGE_COMPROMISE)

Threat actors:
Threat Description

Attackers exploit vulnerabilities in secure storage implementations or gain unauthorized access to storage areas.

Impact

Breach of confidential data stored by Trusted Firmware, such as encryption keys or sensitive configuration settings.
SECURE_STORAGE

CVSS
Environmental score: 8.1 (High)
Vector:CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Counter-measures for SECURE_STORAGE_COMPROMISE

ENCRYPT_STORAGE Encrypt Sensitive Storage

Use strong encryption algorithms to protect data stored by Trusted Firmware, ensuring confidentiality even if storage is compromised.

Countermeasure in place? ✔ Public and disclosable? ✔

Bootloader Exploitation (BOOTLOADER_ATTACK)

Threat actors:
Threat Description

Attackers manipulate the bootloader or inject malicious code during the boot process, compromising the root of trust.

Impact

Exploitation of vulnerabilities in the bootloader to gain unauthorized control over the system or bypass secure boot mechanisms.
FIRMWARE_INTEGRITY
SECURE_BOOT

CVSS
Environmental score: 7.6 (High)
Vector:CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Counter-measures for BOOTLOADER_ATTACK

SECURE_BOOT_VERIFICATION Verify Bootloader Integrity

Use cryptographic signatures to ensure the bootloader has not been tampered with before execution.

Countermeasure in place? ✔ Public and disclosable? ✔

Requests For Information

    Operational Security Hardening Guide

    SeqCountermeasure Details

    Testing guide

    This guide lists all testable attacks described in the threat model

    SeqAttack to testPass/Fail/NA

    Keys classification