Siemens Building X - Security Manager Edge Controller
Monitor6.2ICS-CERT ICSA-25-345-07Dec 9, 2025
Attack VectorLocal
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary
Building X - Security Manager Edge Controller (ACC-AP) devices do not properly verify the integrity of firmware updates. An attacker could upload maliciously modified firmware onto the device if they gain access to the update mechanism. Siemens is preparing fix versions.
What this means
What could happen
An attacker with physical or local network access to the controller could install malicious firmware, allowing them to alter building access control operations, disable security systems, or cause unexpected behavior in physical security functions.
Who's at risk
Building security and access control managers who operate Siemens Building X Security Manager Edge Controller (ACC-AP) devices. This affects organizations relying on these controllers for managing physical access systems, credential readers, and building automation. Any site with ACC-AP devices is potentially affected since all versions are vulnerable and no fix is available.
How it could be exploited
An attacker would need to physically access the device or gain access to the controller's firmware update interface. They could then upload a modified firmware package that bypasses integrity checks, since the device does not properly validate firmware signatures or checksums before installation.
Prerequisites
- Physical access to the controller or network access to the firmware update interface
- Ability to create or obtain a modified firmware package
- Access credentials to the ACC Firmware App or update mechanism (default or compromised credentials)
No patch availableLow attack complexity (local/physical access required)Could affect safety and physical security systemsAffects all versions of the product
Exploitability
Low exploit probability (EPSS 0.1%)
Affected products (1)
ProductAffected VersionsFix Status
Building X - Security Manager Edge Controller (ACC-AP)All versionsNo fix (EOL)
Remediation & Mitigation
0/6
Do now
0/3WORKAROUNDUse the ACC Firmware App to apply updates in a controlled and authenticated manner, ensuring only verified firmware packages from the official SIOS portal are installed
WORKAROUNDValidate firmware integrity by confirming hash values of downloaded firmware before installation
HARDENINGRestrict physical access to controllers and limit network access to authorized personnel only
Schedule — requires maintenance window
0/1Patching may require device reboot — plan for process interruption
HARDENINGEnforce strong credential management for ACC Firmware App and controller accounts; update credentials according to policy
Mitigations - no patch available
0/2Building X - Security Manager Edge Controller (ACC-AP) has reached End of Life. The vendor will not release a patch. Apply the following compensating controls:
HARDENINGLocate controller networks behind firewalls and isolate from business networks
HARDENINGConfigure the controller environment according to Siemens operational guidelines for industrial security as outlined in product manuals
CVEs (1)
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