SSA-420375

Siemens Security Advisory by Siemens ProductCERT

SSA-420375: Improper Integrity Check of Firmware Updates in Building X - Security Manager Edge Controller (ACC-AP)

Publication Date:	2025-12-09
Last Update:	2025-12-09
Current Version:	V1.0
CVSS v3.1 Base Score:	6.2
CVSS v4.0 Base Score:	5.9

SUMMARY

Building X - Security Manager Edge Controller (ACC-AP) devices do not properly check the integrity of firmware updates. This could allow an attacker to upload a maliciously modified firmware onto the device.

Siemens is preparing fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.

KNOWN AFFECTED PRODUCTS

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Affected Product and Versions	Remediation
Building X - Security Manager Edge Controller (ACC-AP) All versions affected by CVE-2022-31807	Currently no fix is planned See further recommendations from section Mitigations

MITIGATIONS

Siemens has identified the following specific mitigations that customers can apply to reduce the risk:

Use the ACC Firmware App to apply updates in a controlled and authenticated manner, ensuring that only verified firmware packages from the official SIOS portal are installed on the controller. Validate the integrity of the downloaded firmware by confirming its hash value. Access to the controller should remain limited to authorized personnel, and credentials must be protected and updated according to policy to reduce the risk of unauthorized modifications or the installation of tampered firmware

Please follow the General Security Recommendations.

GENERAL SECURITY RECOMMENDATIONS

As a general security measure Siemens strongly recommends to protect network access to affected products with appropriate mechanisms. It is advised to follow recommended security practices in order to run the devices in a protected IT environment.

PRODUCT DESCRIPTION

Edge Controller for Building X - Security Manager is a device that is directly connected to the Building X cloud infrastructure and provides physical access to various entry points, such as doors.

VULNERABILITY DESCRIPTION

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This chapter describes all vulnerabilities (CVE-IDs) addressed in this security advisory. Wherever applicable, it also documents the product-specific impact of the individual vulnerabilities.

Vulnerability CVE-2022-31807

Affected devices do not properly check the integrity of firmware updates. This could allow a local attacker to upload a maliciously modified firmware onto the device. In a second scenario, a remote attacker who is able to intercept the transfer of a valid firmware from the server to the device could modify the firmware "on the fly".

CVSS v3.1 Base Score	6.2
CVSS v3.1 Vector	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0 Base Score	5.9
CVSS v4.0 Vector	CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CWE	CWE-347: Improper Verification of Cryptographic Signature

ACKNOWLEDGMENTS

Siemens thanks the following party for its efforts:

Airbus Security for reporting the vulnerability

ADDITIONAL INFORMATION

For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT: https://www.siemens.com/cert/advisories

HISTORY DATA

V1.0 (2025-12-09):

Publication Date

The use of Siemens Security Advisories is subject to the terms and conditions listed on: https://www.siemens.com/productcert/terms-of-use.