CVE-2024-23814: Network Stack ICMP Service DoS Vulnerability

CVE-2024-23814 Overview

CVE-2024-23814 is a resource exhaustion vulnerability [CWE-400] affecting the integrated Internet Control Message Protocol (ICMP) service in the network stack of certain Siemens devices. An unauthenticated remote attacker can send specially crafted messages that target IP fragment reassembly to exhaust available memory. Successful exploitation results in a temporary denial of service (DoS) of the ICMP service. Other communication services on the device remain unaffected, and normal ICMP operation resumes after the attack ends. Siemens documents the issue in advisories SSA-725549 and SSA-769027.

Critical Impact
Remote unauthenticated attackers can disrupt ICMP availability on affected Siemens network stacks by triggering memory exhaustion during IP fragment reassembly.

Affected Products

Siemens devices covered by advisory SSA-725549
Siemens devices covered by advisory SSA-769027
Specific product and firmware versions listed in the linked Siemens ProductCERT advisories

Discovery Timeline

2025-02-11 - CVE-2024-23814 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-23814

Vulnerability Analysis

The flaw resides in the ICMP handling path of the integrated network stack on affected Siemens devices. When the stack processes fragmented IP packets, the reassembly logic allocates buffers to hold pending fragments until the full datagram is available. Specially crafted fragment sequences force the stack to hold memory without releasing it, depleting the pool used by the ICMP service.

Once memory is exhausted, the ICMP service can no longer process legitimate requests. Higher-layer services such as HTTP, industrial protocols, and management interfaces continue to function because they do not share the same reassembly resources. The device recovers automatically once the malicious traffic ceases and buffers are freed.

Root Cause

The root cause is uncontrolled resource consumption in the IP fragment reassembly component of the ICMP subsystem. The stack does not sufficiently limit the number, size, or lifetime of pending fragment buffers when processing attacker-controlled fragment patterns.

Attack Vector

Exploitation requires only network reachability to the target device. No authentication, user interaction, or prior foothold is needed. An attacker sends a sustained stream of crafted fragmented IP packets destined for the device's ICMP service. The attack can be mounted from any host that can route packets to the affected device, including across flat operational technology (OT) network segments. Refer to the Siemens advisories for exploitation prerequisites and mitigations specific to each product family.

Detection Methods for CVE-2024-23814

Indicators of Compromise

Sudden loss of ICMP echo responses from affected Siemens devices while other services remain reachable.
Elevated volumes of fragmented IP traffic (non-final fragments, small MTU fragments, or overlapping offsets) directed at device management interfaces.
Recovery of ICMP responsiveness shortly after suspicious fragment traffic subsides.

Detection Strategies

Baseline normal ICMP and IP fragmentation patterns on OT segments, then alert on deviations targeting industrial endpoints.
Deploy network intrusion detection signatures for anomalous fragment reassembly behavior, including high rates of incomplete fragment sets.
Correlate device availability telemetry with packet capture metadata to distinguish DoS conditions from routine link issues.

Monitoring Recommendations

Continuously monitor reachability and ICMP response latency for critical Siemens devices identified in SSA-725549 and SSA-769027.
Log and review fragmentation-related counters on upstream firewalls, switches, and routers protecting OT subnets.
Forward network and device logs to a centralized analytics platform to support cross-source correlation and historical review.

How to Mitigate CVE-2024-23814

Immediate Actions Required

Identify affected Siemens devices by cross-referencing installed firmware against advisories SSA-725549 and SSA-769027.
Restrict ICMP and fragmented IP traffic to affected devices at perimeter and cell-zone firewalls.
Isolate industrial control networks from untrusted networks per Siemens operational guidelines and IEC 62443.

Patch Information

Apply the firmware updates and follow the product-specific remediation steps documented in the Siemens ProductCERT advisories SSA-725549 and SSA-769027. The advisories list fixed versions, upgrade paths, and any interim mitigations applicable to specific device models.

Workarounds

Block or rate-limit inbound ICMP echo and fragmented IP traffic destined for affected devices where operationally acceptable.
Enforce network segmentation so that only trusted engineering workstations and jump hosts can reach device management interfaces.
Deploy access control lists (ACLs) on adjacent switches and routers to constrain the sources permitted to communicate with vulnerable endpoints.

bash

# Example ACL concept: restrict ICMP and fragments to affected device
# Replace <device_ip> and <trusted_subnet> with environment values
access-list 150 permit icmp <trusted_subnet> 0.0.0.255 host <device_ip>
access-list 150 deny   icmp any host <device_ip>
access-list 150 deny   ip any host <device_ip> fragments
access-list 150 permit ip any host <device_ip>