External risk intelligence

Arm Trusted Firmware-M System Halt and Data Exposure Risk.

CVE advisoryKnown Exploit

CVE-2021-27562

Certain versions of Arm Trusted Firmware M are affected by a flaw that could allow a local attacker to halt a system, overwrite secure data, or expose secure data. This presents a business risk related to system availability and data confidentiality. Organizations should apply vendor security updates to mitigate this r

1Halo Surface Signal

Out-of-bounds Write

Trustedfirmware Trusted Firmware M

1.2.0 and earlier

External exposure likelihood

Halo Surface Signal score for CVE-2021-27562

This vulnerability affects Trusted Firmware-M, which is a low-level, embedded secure software component running on hardware. It is not a network-accessible service or application, and it operates within the internal processing environment of a device, making public internet exposure as a reachable attack surface impossible in normal deployment patterns.

Horizon Alert

Summary of the vulnerability and why it matters

Certain versions of Arm Trusted Firmware M contain a flaw that could allow unauthorized access to secure data or disrupt system operations. This vulnerability arises from how secure functions are called from a non-secure environment. The potential impact includes system halts, overwriting sensitive information, or exposing confidential data.

Vulnerable: Arm Trusted Firmware M
Weakness: Improper handling of secure function calls
Impact: System halt, data overwrite, or data exposure

Attack Path

How an attacker could exploit the issue

An attacker with local access can exploit a vulnerability within Arm Trusted Firmware M. This vulnerability allows the non-secure world to trigger a system halt, overwrite secure data, or expose secure data. The attack occurs when secure functions are called under the non-secure processing environment handler mode.

Requires local access.
Attacker calls secure functions.
Results in system halt or data issues.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability impacts Arm Trusted Firmware M and could allow a local attacker to halt a system, overwrite secure data, or expose secure data. The exploit requires an attacker to have local access and specific conditions within the system. The potential for data corruption or disclosure presents a significant business risk.

Likely attacker skill level: Low
Required access or conditions: Local access required
Business risk or urgency: High

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in Arm Trusted Firmware M could allow local attackers to impact system stability or data integrity. Organizations should prioritize identifying any systems running the affected firmware to understand their exposure. The primary mitigation involves applying the vendor's security updates.

Find affected Arm Trusted Firmware M assets.
Isolate or reduce exposure to risk.
Apply vendor fix and validate.
Monitor for related issues.

Frequently asked questions

What is Arm Trusted Firmware-M and what is its purpose?

Arm Trusted Firmware-M (TF-M) is a foundational software component designed for Arm Cortex-M processors. It establishes a secure execution environment on embedded devices, managing sensitive operations and safeguarding data. TF-M is essential for developing secure applications on microcontrollers.

How does the CVE-2021-27562 vulnerability manifest as a system halt or data corruption?

CVE-2021-27562 is an out-of-bounds write vulnerability. Within TF-M, the non-secure processing environment (NSPE) can inadvertently trigger this flaw when calling a secure function. This can lead to unintended system halts or the overwriting of protected secure data.

What conditions are necessary for an attacker to exploit the TF-M vulnerability?

Exploiting this vulnerability requires an attacker to have local access to the affected system. The attack vector involves calling secure functions from the non-secure processing environment handler mode, which then triggers the out-of-bounds write flaw.

What is the significance of CVE-2021-27562 for system security?

This vulnerability poses a risk to the integrity and confidentiality of secure data on devices utilizing Arm Trusted Firmware-M. It can lead to system instability through halts or data manipulation, impacting the overall security posture of embedded systems.

What steps should be taken to address the Arm Trusted Firmware-M vulnerability?

Organizations should identify all systems running affected versions of Arm Trusted Firmware-M and assess their exposure. The primary remediation is to apply security updates provided by the vendor. It is also advisable to monitor for any related security incidents following the update.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.