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Busch-Welcome® 2 wire Door opener actuator by default in compatibility mode.

Monitor6.89akk108471a4556Jul 21, 2025
Attack VectorPhysical
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary

ABB Switch Actuator 4 DU -83330 devices ship in a default compatibility mode that fails to properly restrict access to the door opening mechanism. An attacker with physical access to the actuator device itself can bypass the normal authorization controls and trigger the door to open without valid credentials, gaining unauthorized access to the building or secured area.

What this means
What could happen
An attacker with physical access to the device could bypass door access controls and gain unauthorized entry to buildings protected by these ABB actuators. This could compromise physical security and allow access to critical infrastructure or sensitive areas.
Who's at risk
Building access control system operators and facility managers who use ABB Switch Actuator 4 DU -83330 devices for door or light control should care. This includes schools, hospitals, office buildings, manufacturing plants, data centers, and any facility relying on these actuators for physical security or environmental controls.
How it could be exploited
An attacker with physical access to the Switch Actuator could exploit the default compatibility mode configuration to override the normal access control logic. The device's default settings fail to enforce proper authentication, allowing direct manipulation of the door opening mechanism without valid credentials or authorization codes.
Prerequisites
  • Physical access to the Switch Actuator 4 DU -83330 device
  • Device must be in default compatibility mode configuration
no patch availabledefault credentials or weak default configurationaffects physical security/safety systemslow technical complexity for exploitation
Exploitability
Low exploit probability (EPSS 0.0%)
Affected products (2)
2 EOL
ProductAffected VersionsFix Status
Switch Actuator 4 DU -83330 - All VersionsAll versionsNo fix (EOL)
Switch actuator, door/light 4 DU -83330-500 - All VersionsAll versionsNo fix (EOL)
Remediation & Mitigation
0/3
Do now
0/1
HARDENINGRestrict physical access to the device itself—ensure the actuator is installed in a location not easily accessible to unauthorized personnel, and consider protective enclosures if possible
Schedule — requires maintenance window
0/1

Patching may require device reboot — plan for process interruption

HOTFIXContact ABB support to confirm if a firmware update or configuration change is available to disable compatibility mode or enforce stronger access controls
Mitigations - no patch available
0/1
The following products have reached End of Life with no planned fix: Switch Actuator 4 DU -83330 - All Versions, Switch actuator, door/light 4 DU -83330-500 - All Versions. Apply the following compensating controls:
HARDENINGReview and manually verify the physical security of door actuator installations; consider adding supplemental mechanical locks or additional physical access controls to doors managed by these devices
View full ABB PSIRT advisory
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