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CVE-2025-3755: Unauthenticated Remote Attack on Mitsubishi Electric MELSEC iQ-F Series CPU modules

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Overview

The Common Vulnerabilities and Exposures system has identified an important vulnerability, CVE-2025-3755, that affects Mitsubishi Electric Corporation MELSEC iQ-F Series CPU modules. These modules used across various industry sectors are exposed to an unauthenticated remote attack that can lead to system compromise or data leakage. The vulnerability primarily involves improper validation of specified index, position, or offset in input, rendering the system susceptible to Denial-of-Service (DoS) attacks or inadvertent shutdown of the CPU module.

Vulnerability Summary

CVE ID: CVE-2025-3755
Severity: Critical (CVSS 9.1)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Unauthenticated access, potential system compromise or data leakage, and Denial-of-Service (DoS) condition.

Affected Products

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Product | Affected Versions

Mitsubishi Electric Corporation MELSEC iQ-F Series CPU modules | All versions prior to the patch

How the Exploit Works

The exploit works by sending specifically crafted packets to the target system. Due to a flaw in the input validation process, an attacker can manipulate the index, position, or offset in input, causing the system to behave unexpectedly. This could lead to unauthorized access to system information, a DoS condition in MELSOFT connection, or an abrupt stop in the CPU module operation causing a DoS condition on the CPU module itself.

Conceptual Example Code

While the specific details of the exploit are highly technical and beyond the scope of this blog post, the conceptual example below illustrates how a malicious HTTP request could be crafted:

POST /target_endpoint HTTP/1.1
Host: vulnerable.iq-f_module.com
Content-Type: application/json
{ "manipulated_index": "..." }

In this example, the `manipulated_index` would contain the malicious payload, crafted in such a way as to exploit the improper input validation vulnerability.

Mitigation

Mitsubishi Electric Corporation has released a patch to address this vulnerability. All users are strongly encouraged to apply the patch as soon as possible. If the patch cannot be applied immediately, users are advised to use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation measure. These steps will help to limit the potential damage caused by an unauthenticated attacker exploiting this vulnerability.

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Disclaimer:

The information and code presented in this article are provided for educational and defensive cybersecurity purposes only. Any conceptual or pseudocode examples are simplified representations intended to raise awareness and promote secure development and system configuration practices.

Do not use this information to attempt unauthorized access or exploit vulnerabilities on systems that you do not own or have explicit permission to test.

Ameeba and its authors do not endorse or condone malicious behavior and are not responsible for misuse of the content. Always follow ethical hacking guidelines, responsible disclosure practices, and local laws.

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