CVE-2022-40504 in 315 5G IoT Modem
Summary
by MITRE • 05/02/2023
Transient DOS due to reachable assertion in Modem when UE received Downlink Data Indication message from the network.
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2022-40504 represents a transient denial of service condition affecting modem implementations within cellular network infrastructure. This issue manifests when a user equipment device receives a Downlink Data Indication message from the network, triggering an assertion that leads to system disruption. The problem resides within the modem's handling of network signaling messages, specifically in the processing path that manages data delivery notifications from the base station or network controller to the mobile device.
The technical flaw stems from an unreachable assertion within the modem's software stack that fails to properly validate incoming Downlink Data Indication messages. When such a message is received, the modem's state machine encounters an unexpected condition that triggers an assertion failure, causing the device to enter a non-functional state. This assertion failure typically occurs in the data handling or protocol parsing components of the modem firmware, where the system expects certain message formats or sequence numbers that may not be present in the received data indication. The vulnerability is classified as transient because the device typically recovers after a reboot or power cycle, but the disruption can occur during critical communication periods, potentially leading to service interruption.
From an operational impact perspective, this vulnerability affects cellular network reliability and user experience, particularly in scenarios where continuous connectivity is required. The denial of service condition can occur during critical communication events such as emergency calls, location services, or data transmission activities. The vulnerability may be exploited by attackers who can send malformed Downlink Data Indication messages to specific user equipment devices, causing temporary service disruption. Network operators may experience increased support tickets, user complaints, and potential service degradation during exploitation periods. The impact extends beyond individual devices to potentially affect network-wide service quality if multiple devices are simultaneously targeted.
The vulnerability aligns with CWE-617, reachable assertion, which describes conditions where assertions in code can be triggered by external inputs, leading to program termination or unexpected behavior. This weakness is particularly concerning in telecommunications infrastructure where system reliability is paramount. The issue also maps to ATT&CK technique T1499.004, "Endpoint Denial of Service," as it represents a method of causing temporary service disruption through manipulation of device state. Mitigation strategies should include firmware updates from device manufacturers, implementation of message validation checks within network infrastructure, and potential network-level filtering of suspicious Downlink Data Indication messages. Additionally, implementing robust error handling and graceful degradation mechanisms within modem implementations can prevent assertion failures from causing complete system shutdowns. Network operators should also consider monitoring for unusual patterns in Downlink Data Indication message traffic that may indicate exploitation attempts.