Kaden PICOFLUX Air Wireless M-Bus Mode 5 AES-128-CBC IV Weakness Privacy Leak

Vulnerability Key Information Affected Component Kaden PICOFLUX Air (specific version unknown) Technical Details The meter sends two types of messages: short messages (48 bytes) and long messages (containing metering values). Security mode is Wireless M-Bus Mode 5, using an 8-bit counter to generate the IV for AES-128-CBC encryption. The counter overflows every 256 messages. Due to flaws in the encryption mode, attackers may infer consumption activity (e.g., water usage) by observing repeating counter values and changes in the last 16 bytes. CVSS Score CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Base Score: 4.3 (Medium severity) Attack Vector Attacker must be in close proximity to the meter (within tens of meters; potentially farther with a good antenna). Attack Complexity Attacker only needs a publicly available Wireless M-Bus T1 reader. Privileges and User Interaction Required None. Attackers can locate meters via signal strength. Impact Confidentiality: Attackers can infer consumption activity (e.g., water usage). Integrity and Availability: No direct impact. CWE CWE-203: Observable Differences Risk Attackers can gain insights into household activities. Attackers can detect zero consumption, inferring that no one is home. Recommendations The meter’s encryption may not be configurable; consider replacing the meter. Further Reading POLČÁK Libor. Wireless M-Bus: Kdo vý, I'e perete? (Czech) POLČÁK Libor and MATOUČEK Petr. Metering Homes: Do Energy Efficiency and Privacy Need to be in Conflict?

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Kaden PICOFLUX Air Wireless M-Bus Mode 5 AES-128-CBC IV Weakness Privacy Leak