CVE-2023-37006 in MME
Summary
by MITRE • 01/22/2025
Open5GS MME versions <= 2.6.4 contain an assertion that can be remotely triggered via a malformed ASN.1 packet over the S1AP interface. An attacker may send a `Handover Request Ack` message missing a required `MME_UE_S1AP_ID` field to repeatedly crash the MME, resulting in denial of service.
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Analysis
by VulDB Data Team • 01/22/2025
The vulnerability identified as CVE-2023-37006 affects Open5GS MME components version 2.6.4 and earlier, representing a critical denial of service weakness within the 5G core network infrastructure. This flaw manifests through improper handling of ASN.1 encoded packets transmitted over the S1AP interface, which serves as the primary communication channel between eNodeBs and the MME in 4G/LTE networks. The specific assertion failure occurs when processing a malformed Handover Request Ack message, demonstrating a fundamental lack of input validation and error handling in the protocol stack implementation.
The technical execution of this vulnerability requires an attacker to craft and transmit a specially formatted Handover Request Ack message that deliberately omits the mandatory MME_UE_S1AP_ID field. This field is essential for maintaining proper session state and tracking UE (User Equipment) connections within the MME. When the MME receives such a malformed packet, it fails to properly validate the presence of this required field and subsequently triggers an assertion failure that causes the process to crash. The vulnerability is particularly concerning because it can be repeatedly exploited, allowing an attacker to continuously disrupt service by sending multiple malformed packets, effectively maintaining a persistent denial of service condition.
The operational impact of CVE-2023-37006 extends beyond simple service disruption, as it undermines the reliability and availability of the entire 5G core network infrastructure. Mobile network operators relying on affected Open5GS MME versions face significant risk of service degradation or complete outage of their network services, particularly during critical network operations such as handovers between cells. This vulnerability directly impacts the network's ability to maintain consistent connectivity for subscribers and can result in widespread service disruption across multiple geographic regions. The attack vector through the S1AP interface means that exploitation can occur from external network positions, making it particularly dangerous for operators who do not adequately segment their network infrastructure.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected Open5GS MME components to version 2.6.5 or later, which includes the necessary code fixes to properly validate ASN.1 packet structures and handle missing mandatory fields gracefully. Network operators should also implement network segmentation and access controls to limit exposure of the S1AP interface to untrusted networks, following the principle of least privilege as outlined in the NIST Cybersecurity Framework. Additional defensive measures include implementing rate limiting and anomaly detection mechanisms on the S1AP interface to identify and block suspicious packet patterns, as well as establishing monitoring procedures to detect service disruptions that may indicate exploitation attempts. This vulnerability aligns with CWE-682, which covers incorrect arithmetic operations, and maps to ATT&CK technique T1499.004 for network disruption attacks, emphasizing the need for comprehensive security controls beyond simple patch management to protect against such sophisticated network-level threats.