CVE-2023-37025

Executive Summary

CVE-2023-37025 is a null pointer dereference vulnerability in the Mobile Management Entity (MME) component of Magma versions up to and including 1.8.0. A network-adjacent attacker can crash the MME by sending a crafted S1AP Reset packet that is missing the mandatory ResetType field. The impact is a denial of service condition affecting the control plane of Magma-based LTE/5G networks; the vulnerability is fixed in Magma v1.9 at commit 08472ba98b8321f802e95f5622fa90fec2dea486.

Technical Analysis

The Magma project is an open-source telecom software stack that provides implementations of core network functions for LTE and 5G. One of these functions is the MME, or Mobile Management Entity, which is responsible for signaling, authentication, mobility, and session management for user equipment (UE) attached to the radio access network.

The vulnerability resides in the handling of the S1AP protocol, which is used over the S1-MME interface between an eNodeB (base station) and the MME. S1AP messages are encoded using ASN.1 and transported over SCTP. The Reset message in S1AP is used to reinitialize the context between an eNodeB and the MME, typically after a failure or restart.

Per the NVD description, the MME in Magma <= 1.8.0 contains a null pointer dereference triggered by an S1AP Reset packet that is missing an expected ResetType field. In the S1AP specification, ResetType is a mandatory information element of the Reset procedure. If an attacker sends a malformed Reset PDU where ResetType is absent or truncated, the MME's decoder proceeds to access the missing object and dereferences a null pointer. This causes an exception in the MME process, leading to a crash and an availability impact.

The exact code path has not been publicly described in the available data. The NVD entry does not provide a CWE, CVSS vector, or additional technical detail beyond the S1AP message-level trigger. The vendor patch is claimed by OSV to be contained in Magma v1.9 commit 08472ba98b8321f802e95f5622fa90fec2dea486, but this has not been independently confirmed.

Attack surface considerations:

• The MME is a control-plane component that is reachable from the radio access network or from an adjacent node able to inject SCTP traffic toward the S1-MME interface.
• The malicious packet does not require authentication if the attacker can spoof or emulate an S1AP peer.
• The vulnerability is a logic/parsing flaw in the S1AP message decoder, not an injection flaw requiring complex payload encoding.

Exploitation Scenarios

No public proof-of-concept is known at the time of writing. The attack chain below is inferred from the NVD description and the vulnerability class.

1. Reconnaissance / target identification: An attacker with network adjacency to the S1-MME interface or the transport network segment serving the MME identifies the MME's SCTP endpoint. This could be done by scanning for SCTP services on commonly used S1AP ports, identifying eNodeB-to-MME signaling traffic, or by having compromised a node on the same transport network.

2. Triggering the flaw: The attacker crafts an S1AP Reset message but deliberately omits the ResetType information element. Because the S1AP decoder in Magma expects ResetType to be present, the MME's processing logic attempts to read the value from a null pointer during parsing. The malformed packet is within the bounds of attacker control and does not require authentication beyond the SCTP/S1AP session.

3. Payload / execution method: At the vulnerability-class level, this is a null pointer dereference caused by insufficient validation of mandatory protocol fields. The attacker does not need to deliver arbitrary code; the malformed protocol message itself is the payload. The packet is sent as a single SCTP/S1AP message to the MME.

4. Post-exploitation impact: When the null pointer dereference occurs, the MME process crashes and may enter a restart or permanently unavailable state. During the outage, all UEs served by the MME cannot attach, authenticate, perform handovers, or update their location. This disrupts service at the tracking-area or MME-pool level, depending on network architecture. An attacker positioned to repeatedly send the packet can maintain the denial of service condition.

Impact Assessment

• Confidentiality impact: None expected. A null pointer dereference does not normally allow data exfiltration.
• Integrity impact: None expected. No data tampering or configuration modification is implied.
• Availability impact: High. The MME is a central control-plane element; crashing it denies service to all attached UEs and disrupts mobility and registration signaling.
• Business impact: For an operator deploying Magma as a core network, exploitation of this CVE can cause a partial or full mobile network service outage. Revenue loss, user-facing degradation, and potential regulatory/penalty implications for violating availability commitments may follow.
• CVSS considerations: NVD has assigned N/A for both the CVSS score and vector. This is likely due to insufficient scoring data. The lack of a score should not be interpreted as low severity; the availability impact to an operator is significant.
• Exploitability: EPSS score is 0.00373, indicating a low current probability of exploitation in the wild, but the attack surface is exposed to network-adjacent attackers. There is no evidence of active exploitation or inclusion in CISA KEV.

Detection Guidance

Detection of CVE-2023-37025 requires a combination of deep packet inspection for S1AP/SCTP traffic and monitoring of MME process health. The following rules are intended to be adapted to the organization's logging and monitoring stack. They are most reliable when the MME platform produces process-crash or syslog events and when S1AP packet captures or network telemetry are available.

Sigma Rule

title: Magma MME Process Crash - Potential CVE-2023-37025
id: 4c1777f0-4b9a-4f2c-9b7d-4abf3a2c9c44
status: experimental
description: Detects Magma MME process crash events that may indicate exploitation of CVE-2023-37025 S1AP Reset malformed packet.
logsource:
  product: linux
  service: syslog
detection:
  selection:
    message|contains|all:
      - 'mme'
      - 'segfault'
      - 'SIGSEGV'
      - 'signal 11'
  condition: selection
level: high
tags:
  - attack.t1499
  - cve.2023-37025

YARA Rule

This YARA rule is designed to detect scripts or tooling that may be used to craft S1AP Reset packets for CVE-2023-37025. It does not detect the malicious packet itself but rather attack artifacts on a compromised host.

rule CVE_2023_37025_S1AP_Reset_Exploit_Tooling
{
    meta:
        author = "ValtersIT"
        description = "Detects scripts/tools referencing S1AP Reset and ResetType fields associated with CVE-2023-37025"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-37025"
        date = "2026-04-26"

    strings:
        $s1ap = "S1AP" ascii nocase
        $reset = "Reset" ascii nocase
        $resettype = "ResetType" ascii nocase
        $sctp = "sctp" ascii nocase

    condition:
        all of them and filesize < 2MB
}

Suricata IDS Rule

alert sctp any any -> any 36412 (msg:"CVE-2023-37025 S1AP Reset Missing ResetType DoS Attempt"; flow:to_server; content:"|00 11|"; within:8; reference:cve,2023-37025; classtype:attempted-dos; sid:202337025; rev:1; metadata:created_at 2026_04_26, updated_at 2026_04_26;)

Note: The content pattern |00 11| is a heuristic used to represent the S1AP Reset procedure code. Because S1AP is ASN.1 PER encoded, the exact byte sequence should be validated against packet captures from the Magma environment before production deployment. Consider tuning the rule with SCTP stream reassembly and S1AP decoder alerts if available.

Elastic Detection

Use EQL to detect MME process termination with exit codes consistent with a null pointer dereference crash. On Linux, SIGSEGV results in exit code 139, and SIGABRT results in exit code 134.

process where event.type == "end" and process.name == "mme" and (exit_code == 139 or exit_code == 134 or exit_code == 11)

If network-level data is ingested into Elastic, an additional EQL query can flag SCTP traffic to the S1-MME port:

network where network.transport == "sctp" and destination.port == 36412 and event.outcome == "failure"

Splunk SPL Query

Monitor MME syslog and process telemetry for crash indicators:

index=* sourcetype=linux_syslog "mme" ("SIGSEGV" OR "segfault" OR "signal 11") 
| stats count as crash_count min(_time) as first_seen max(_time) as last_seen by host, source, program

For network-based visibility into S1AP traffic:

index=* sourcetype=cisco:asa OR sourcetype=netflow dest_port=36412 
| stats count as attempts by src_ip, dest_ip, dest_port 
| sort - attempts

Wazuh OSSEC Rule

<group name="magma,cve-2023-37025,">
  <rule id="100370" level="12">
    <decoded />
    <program_name>^mme</program_name>
    <match>Segmentation fault|SIGSEGV|signal 11</match>
    <description>Magma MME process crash - possible CVE-2023-37025 S1AP Reset exploitation</description>
    <group>pci_dss_11.4,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 2/4 (CLAIMED); the patch is referenced by a single source (OSV) but has not been independently confirmed in the vendor advisory data provided. Until validation is complete, treat the upgrade guidance as provisional.

1. Immediate mitigations:

   • Restrict network access to the S1-MME interface. Ensure only authorized eNodeBs and operational management systems can initiate SCTP connections toward the MME.
   • Deploy SCTP/S1AP-aware access control lists or transport-layer filtering to prevent unknown or unexpected peers from reaching the MME.
   • Monitor MME process health and implement automatic restart with crash-loop protection. Organize MME deployments in a redundant architecture so a single MME crash does not cause whole-network service loss.
   • If DPI capability is available, add temporary rules to flag or block S1AP Reset messages that do not contain the mandatory ResetType information element.

2. Patch / upgrade steps:

   • Upgrade Magma to version 1.9 or later. The referenced fix is commit 08472ba98b8321f802e95f5622fa90fec2dea486 in the Magma repository.
   • If a direct upgrade is not immediately possible, verify whether the commit is available as a backport to the deployed release branch.
   • Before patching, test the MME S1AP handling in a staging environment with malformed Reset packets to confirm the crash is resolved.

3. Long-term hardening:

   • Add S1AP protocol fuzzing to the pre-release testing pipeline to catch null pointer dereferences and missing mandatory field errors.
   • Require mutual authentication or transport layer security where feasible on S1 interfaces.
   • Segment the transport network so that an attacker who compromises a small cell or backhaul node cannot directly reach the MME control plane.
   • Maintain an internal CVE watchlist for Magma MME protocol parser changes and consume upstream security advisories as they become available.

References

• NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2023-37025
• OSV Vulnerability Entry: https://osv.dev/vulnerability/CVE-2023-37025
• Magma GitHub Repository (patch commit reference): https://github.com/magma/magma/commit/08472ba98b8321f802e95f5622fa90fec2dea486
• CISA KEV: Not applicable — CVE-2023-37025 is not listed on CISA's Known Exploited Vulnerabilities catalog.

No known threat actor campaigns or exploit-in-the-wild evidence were identified in the provided data. The EPSS score of 0.00373 indicates a below-average current exploitation likelihood.