A new vulnerability, classified under CVE-2024-8936, has been discovered in the Common Vulnerabilities and Exposures database. This vulnerability is a result of improper input validation, also known as CWE-20, and can lead to loss of controller memory confidentiality after a successful Man-In-The-Middle (MITM) attack followed by sending a carefully crafted Modbus function call used to tamper with memory. In this post, we will delve deeper into the details of this vulnerability, explore potential code snippets, provide links to original references, and examine its exploit details.

Vulnerability Details

CWE-20: Improper Input Validation is a security weakness that occurs when an application does not perform the necessary validation on the input it receives, resulting in unintended behavior or the exposure of sensitive information. In the case of CVE-2024-8936, the vulnerability exists in a particular Modbus function call. Modbus is a popular communication protocol used in industrial control systems (ICS), enabling communication between various devices such as programmable logic controllers (PLCs), sensors, and actuators.

Successful Man-In-The-Middle (MITM) Attack

The first step is to conduct a MITM attack, which allows an attacker to intercept, read, modify, and inject new messages into the communication between two devices. This could be achieved by exploiting weaknesses in the network infrastructure or by manipulating the targeted devices. Reference: Man-In-The-Middle Attack Example

Sending Crafted Modbus Function Call

After a successful MITM attack, the attacker can send a crafted Modbus function call to alter memory. Below is an example of a code snippet that can be used to perform this attack:

import pymodbus
from pymodbus.client.sync import ModbusTcpClient

client = ModbusTcpClient("target_IP_address")
client.connect()

# Crafted Modbus function call
crafted_request = pymodbus.write_single_register.WriteSingleRegisterRequest(
    register_address, crafted_data
)
response = client.execute(crafted_request)

client.close()

Using this code, an attacker can modify specific register addresses and data values to manipulate memory allocations. Reference: Python Modbus Library (pymodbus)

Tampering with Memory

By tampering with memory, an attacker can gain access to sensitive information, potentially causing severe damage as the manipulated data will impact the entire system. This may lead to unauthorized access to the controller's memory and could result in the loss of confidentiality.

Implement proper input validation techniques on all the function calls.

2. Use encryption and authentication methods for Modbus protocol, such as Modbus Secure (MBAP+TLS), to protect against MITM attacks.

Conclusion

CVE-2024-8936, a CWE-20 vulnerability, poses a significant threat to the security and confidentiality of industrial systems relying on Modbus protocol. By understanding the details of the exploit and possible attack methods, security professionals can better assess and mitigate the risks associated with this vulnerability.

Stay informed about the latest vulnerabilities and exploits by visiting the following resources

1. Common Vulnerabilities and Exposures (CVE) Database
2. Common Weakness Enumeration (CWE) List
3. National Vulnerability Database (NVD)

Remember, keeping your systems up-to-date and deploying robust security measures are crucial in safeguarding them against the ever-evolving threats.

Timeline

Published on: 11/13/2024 04:23:59 UTC