CVE-2022-41972 in Contiki-NG
Summary
by MITRE • 12/16/2022
Contiki-NG is an open-source, cross-platform operating system for Next-Generation IoT devices. Versions prior to 4.9 contain a NULL Pointer Dereference in BLE L2CAP module. The Contiki-NG operating system for IoT devices contains a Bluetooth Low Energy stack. An attacker can inject a packet in this stack, which causes the implementation to dereference a NULL pointer and triggers undefined behavior. More specifically, while processing the L2CAP protocol, the implementation maps an incoming channel ID to its metadata structure. In this structure, state information regarding credits is managed through calls to the function input_l2cap_credit in the module os/net/mac/ble/ble-l2cap.c. Unfortunately, the input_l2cap_credit function does not check that the metadata corresponding to the user-supplied channel ID actually exists, which can lead to the channel variable being set to NULL before a pointer dereferencing operation is performed. The vulnerability has been patched in the "develop" branch of Contiki-NG, and will be included in release 4.9. Users can apply the patch in Contiki-NG pull request #2253 as a workaround until the new package is released.
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Analysis
by VulDB Data Team • 01/13/2023
The vulnerability CVE-2022-41972 represents a critical NULL pointer dereference flaw within the Contiki-NG operating system's Bluetooth Low Energy stack implementation. This issue affects versions prior to 4.9 and specifically targets the BLE L2CAP (Logical Link Control and Adaptation Protocol) module that serves as a fundamental component for IoT device communication. The Contiki-NG system, designed for next-generation Internet of Things applications, provides a cross-platform environment where this vulnerability can be exploited to disrupt normal operations. The flaw exists within the os/net/mac/ble/ble-l2cap.c module where the input_l2cap_credit function fails to validate channel metadata existence before attempting pointer operations, creating a dangerous condition that can lead to system instability or complete failure.
This technical vulnerability stems from inadequate input validation within the L2CAP protocol processing logic. When an attacker injects malicious packets into the BLE stack, the system attempts to map incoming channel IDs to their corresponding metadata structures for credit management. The function input_l2cap_credit performs operations without verifying whether the metadata structure for the supplied channel ID actually exists, allowing the channel variable to be assigned NULL values. Subsequent pointer dereferencing operations then trigger undefined behavior, potentially causing system crashes or allowing for further exploitation. The vulnerability manifests as a classic null pointer dereference pattern that aligns with CWE-476, which specifically addresses NULL pointer dereference conditions in software implementations. This type of flaw is particularly dangerous in embedded IoT systems where reliability and continuous operation are paramount for device functionality and network stability.
The operational impact of CVE-2022-41972 extends beyond simple system crashes to potentially compromise entire IoT network infrastructures. In practical deployment scenarios, this vulnerability could allow attackers to perform denial-of-service attacks against IoT devices running affected Contiki-NG versions, disrupting critical communication channels and potentially enabling more sophisticated exploitation techniques. The nature of BLE communication in IoT environments means that this vulnerability could affect a wide range of devices including sensors, actuators, and gateway systems that rely on reliable Bluetooth connectivity. The undefined behavior resulting from the NULL pointer dereference could also potentially be leveraged to execute arbitrary code or escalate privileges within the device's operating environment, particularly when combined with other vulnerabilities in the system architecture. From an attacker perspective, this flaw aligns with ATT&CK technique T1499.001 which involves network denial-of-service attacks.
Mitigation strategies for this vulnerability require immediate attention from system administrators and device operators. The recommended approach involves upgrading to Contiki-NG version 4.9 or applying the patch from pull request #2253 available in the development branch. Organizations should prioritize patching their IoT device fleets to prevent exploitation, particularly those operating in critical infrastructure environments where device reliability is essential. Additional defensive measures include network monitoring to detect anomalous BLE packet injection patterns and implementing proper input validation at network boundaries. Security teams should also consider isolating affected IoT devices from critical network segments until patches are applied and conduct thorough vulnerability assessments of their IoT deployments to identify other potential instances of similar null pointer dereference conditions within the system architecture. The fix addresses the root cause by implementing proper validation checks in the input_l2cap_credit function, ensuring that channel metadata structures are verified before any pointer operations are performed, thereby preventing the dangerous NULL assignment that leads to the undefined behavior.