Attack Chain

1. The attacker identifies a SIMATIC CN 4100 device running a version prior to V5.0.
2. The attacker establishes a TCP connection with the target device.
3. The attacker floods the target with a high volume of TCP SYN packets.
4. The device attempts to allocate resources for each incoming SYN packet.
5. Due to the high volume, the device’s memory and CPU resources are rapidly consumed.
6. The device becomes unresponsive to legitimate requests.
7. The SIMATIC CN 4100 service becomes unavailable.
8. A denial-of-service condition is achieved, disrupting network operations.

Impact

Successful exploitation of CVE-2026-22925 results in a denial-of-service condition on the SIMATIC CN 4100 device. This can disrupt network operations and potentially lead to financial losses due to downtime. The number of affected devices and sectors is unknown, but any organization using vulnerable versions of SIMATIC CN 4100 is at risk. If the attack succeeds, critical network functions may be unavailable, leading to operational disruptions and potential safety concerns.

Recommendation

• Upgrade SIMATIC CN 4100 to version V5.0 or later to patch CVE-2026-22925, as per the Siemens advisory.
• Implement rate limiting on network devices to mitigate the impact of TCP SYN floods, as the vulnerability is triggered by a high volume of SYN packets.
• Deploy the Sigma rule Detect Suspicious TCP SYN Flood to identify potential exploitation attempts targeting SIMATIC CN 4100 devices.