CVE-2023-37010 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 an `eNB Status Transfer` 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-2023-37010 affects Open5GS MME components running version 2.6.4 or earlier, representing a critical denial of service weakness within the 5G core network infrastructure. This flaw manifests through improper handling of malformed ASN.1 packets transmitted over the S1AP interface, which serves as the control plane protocol connecting eNodeBs to the MME in 4G/LTE networks and their 5G equivalents. The vulnerability specifically targets the MME's assertion mechanism that validates incoming eNB Status Transfer messages, creating a condition where the system crashes when encountering missing mandatory fields.
The technical implementation of this vulnerability exploits the absence of proper input validation within the S1AP message processing pipeline. When an attacker sends a malformed eNB Status Transfer message lacking the required MME_UE_S1AP_ID field, the MME's assertion logic fails and terminates the process. This assertion failure occurs because the system assumes the presence of this critical field without proper defensive programming measures. The vulnerability operates at the application layer of the network stack, leveraging the S1AP protocol's structure where eNB Status Transfer messages are used for conveying status information between the eNodeB and MME during various network operations. The flaw stems from inadequate error handling and missing null pointer checks within the MME's message parsing routines.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited to systematically crash the MME service through repeated attacks. An attacker requires only minimal network access to send malformed packets over the S1AP interface, making the attack surface relatively broad and accessible. The repeated triggering of assertions can cause the MME to continuously restart, leading to extended periods of network unavailability for connected mobile subscribers. This denial of service scenario directly affects network availability and can cause cascading effects throughout the mobile core network infrastructure, potentially disrupting emergency services and critical communications. The vulnerability affects the core network's ability to maintain stable connections with mobile devices and can severely impact network performance metrics.
Mitigation strategies for CVE-2023-37010 should prioritize immediate software updates to versions 2.6.5 or later where the assertion handling has been corrected. Network administrators should implement traffic filtering mechanisms at the S1AP interface to detect and block malformed packets before they reach the MME. The deployment of intrusion detection systems specifically configured to monitor for S1AP protocol anomalies can provide early warning of attempted exploitation. Additionally, implementing rate limiting on incoming S1AP messages and establishing redundant MME instances can help maintain service availability during potential attacks. Organizations should also consider implementing network segmentation to isolate critical MME components from less secure network segments, reducing the potential impact of successful exploitation attempts.
This vulnerability aligns with CWE-617, which addresses reachable assertions that can be triggered through external input, and represents a classic example of improper input validation within telecommunications protocols. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network disruption attacks targeting network infrastructure components. The weakness demonstrates how protocol-level flaws in core network infrastructure can create significant security implications, particularly in 5G networks where the MME plays a crucial role in session management and mobility control. The vulnerability also highlights the importance of defensive programming practices and proper error handling in mission-critical network components where reliability and availability are paramount for maintaining service continuity.