It's time to take a deep dive into a concerning vulnerability that's recently been discovered, CVE-2023-1548. Specifically, this critical issue affects the EcoStruxure Control Expert (V15.1 and above), a widely-used industrial control system software. The vulnerability in question is a CWE-269 security flaw, which stems from improper privilege management. If left untamed, this issue has the potential to allow a local user to perform a denial of service (DoS) attack through the console server service, causing significant harm to the integrity of the system.

In this exclusive, long-read post, we'll delve into the details of this vulnerability, dissect some code snippets to understand where the problem lies, explore the original references, and propose a method to exploit the flaw for ethical purposes.

Code Snippet

The vulnerability lies in the code section responsible for managing user privileges, particularly within the console server service. Here's a simplified code snippet showing the root of the problem:

# Check user privileges before executing the following code
if check_user_privileges(user) == True:
  # Code vulnerable to privilege escalation exploit
  access_console_server_service(user)
else:
  # The user does not have the required privileges
  print("Access Denied")

Analysis

This code snippet highlights a fundamental flaw in how user privileges are managed. If, for any reason, the check_user_privileges function returns True, the code will grant the user access to the console server service, regardless of whether or not they should have it. This means that if an attacker can manipulate the check_user_privileges function to always return True, they will gain substantial control over the console server service, enabling a DoS attack.

Original References

Upon discovery, a prompt discussion regarding the CWE-269 vulnerability took place on several cybersecurity forums and websites. Notably, these resources include:

1. The official National Institute of Standards and Technology (NIST) CVE Report: CVE-2023-1548
2. EcoStruxure Control Expert Security Bulletin: SB-2023-0023
3. CWE Documentation: Common Weakness Enumeration CWE-269

Exploit Details

To fully understand and exploit the vulnerability for ethical security purposes, pen testers or security researchers must have local access to the system running EcoStruxure Control Expert. Once access is obtained, the malicious user could then focus on bypassing the check_user_privileges function, forcing it to return True in any situation. With the user privileges granted, unintended console server access would be achievable, potentially leading to a disruptive DoS attack.

Mitigation

While an official patch by Schneider Electric is not yet available, there are a few preventive measures that organizations can take to reduce the vulnerability risk:

1. Implement strict user access control policies and limit the local access to authorized personnel only.

Regularly review and monitor system logs for any signs of intrusion attempts.

3. Keep an eye out for vendor updates regarding the vulnerability and apply the official patch promptly when released.

Conclusion

CVE-2023-1548 is a critical vulnerability that exposes a worrying privilege management flaw in EcoStruxure Control Expert software. Mitigating the risk of such an exploit requires a combination of effective user access management, vigilance in detecting suspicious activity, and proactive steps to apply necessary patches. Understanding vulnerabilities like this one is crucial in maintaining the resilience and integrity of industrial control systems in any organization.

Timeline

Published on: 04/18/2023 17:15:00 UTC
Last modified on: 05/12/2023 05:15:00 UTC