Actuator manipulation via lost KNX sequence numbers
Published Jun 5, 2024 · Updated Mar 27, 2025
Replay protection failure in ABB KNX Secure displays and BCUs allows attackers to inject captured telegrams after bus power loss. Affected firmware does not persist KNX telegram sequence numbers across a bus power failure, so the last message is accepted when replayed with an incremented number. Access to the local KNX bus and a power interruption are required; accepted telegrams impersonate a device and can operate lights, blinds, HVAC, or doors.
Summary
What happened
Replay protection failure in ABB KNX Secure displays and BCUs allows attackers to inject captured telegrams after bus power loss. Affected firmware does not persist KNX telegram sequence numbers across a bus power failure, so the last message is accepted when replayed with an incremented number. Access to the local KNX bus and a power interruption are required; accepted telegrams impersonate a device and can operate lights, blinds, HVAC, or doors.
The record
- CVE
- CVE-2024-4009
- Published
- Jun 5, 2024
- Updated
- Mar 27, 2025
- Vendor
- GENEREX SYSTEMS Computervertriebsgesellschaft mbH
- Product
- BCU KNX, BA-U1.0.21
- Classifications
- CWE-294, T0831
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 5, 2024CVE publishedPublication date reported by the CVE source.
- Mar 27, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=1.3.0.33
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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