Executive Summary

This vulnerability is a denial-of-service (DoS) issue in the TCP communication function of Mitsubishi Electric's MELSEC iQ-F Series CPU modules. It occurs due to improper validation of specified quantity in input, allowing a remote attacker to send specially crafted TCP packets that disconnect an active TCP connection. The DoS impact is limited to the attacked TCP connection only, and other connections remain unaffected. Recovery requires re-establishing the disconnected TCP connection. [1, 2]

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Impact Analysis

The vulnerability can cause a denial-of-service condition by disconnecting an active TCP connection remotely. This means that an attacker can disrupt communication with the affected MELSEC iQ-F Series CPU module by targeting its TCP connection, causing temporary unavailability of that connection. However, other concurrent connections are not affected, and normal operation can resume once the TCP connection is re-established. [1, 2]

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Detection Guidance

This vulnerability can be detected by monitoring for unexpected TCP connection disconnections to Mitsubishi Electric MELSEC iQ-F Series CPU modules. Since the attack involves specially crafted TCP packets causing disconnections, network administrators should look for abnormal TCP resets or connection drops targeting these devices. Specific detection commands are not provided in the resources. However, general network monitoring tools like tcpdump or Wireshark can be used to capture and analyze TCP traffic to these devices for unusual patterns or resets. [1, 2]

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Mitigation Strategies

Immediate mitigation steps include restricting physical access to the affected MELSEC iQ-F Series CPU modules and their connected LANs to reduce the risk of exploitation. Additionally, if Internet access to these devices is necessary, use a Virtual Private Network (VPN) to encrypt communications and protect against remote attacks. Since no patch or fixed firmware is planned, these mitigation and avoidance measures are recommended to minimize exposure. [2]

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