CVE-2025-24812 - Vulnerability in SIMATIC S7-120 CPUs Can Allow Denial-of-Service (DoS) Attacks

A recently discovered vulnerability, identified as CVE-2025-24812, is known to affect various versions of SIMATIC S7-120 CPU devices. This vulnerability allows an attacker to cause a denial of service (DoS) by sending specific, specially crafted malicious packets to port 102/tcp. In this post, we'll take a deep dive into the affected devices, exploit details, code snippet, and provide links to the original references.

Affected Devices

The vulnerability affects all versions of the following SIMATIC S7-120 CPU devices with firmware version less than V4.7:

Exploit Details

The devices mentioned above possess an issue in processing specific packets sent to port 102/tcp, making them vulnerable to DoS attacks. An attacker can exploit this vulnerability by sending specially crafted malicious packets to the targeted device. As a result, it could cause the targeted device to stop functioning, effectively initiating a denial of service.

Code Snippet

Here is a sample pseudo-code snippet that demonstrates how a specially crafted packet can be sent to the affected device to exploit the vulnerability:

import socket

def exploit_vulnerability(target_ip):
    crafted_packet = create_malicious_packet()  # Replace this function with actual crafted packet generation
    target_port = 102

    # Create a socket connection
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((target_ip, target_port))

    # Send the malicious packet to the target device
    s.send(crafted_packet)

    # Close the connection
    s.close()

# Replace 'target_ip' with the actual target device IP
exploit_vulnerability('target_ip')

This code snippet shows how an attacker can create a crafted packet, establish a connection with an affected device at port 102, and send the malicious packet to cause the device to stop functioning.

Original References

- ICS Advisory (ICSA-22-099-05): https://us-cert.cisa.gov/ics/advisories/icsa-22-099-05
- Siemens Security Advisory (SSA-681808): https://cert-portal.siemens.com/productcert/pdf/ssa-681808.pdf

Conclusion

To mitigate the risk of exploitation, it is recommended that users apply the latest firmware updates (Version V4.7 or newer) provided by Siemens. Moreover, enhancing network segmentation and applying appropriate access control rules on the control network can also help to limit the attack surface.

Keep your devices up-to-date and follow security best practices to ensure that your systems remain protected from any potential cybersecurity threats.

Timeline

Published on: 02/11/2025 11:15:17 UTC