Attack Chain

1. An attacker identifies a vulnerable Moxa router, such as a TN-4900 series running firmware v3.22 or prior.
2. The attacker exploits CVE-2026-3867 (Improper Ownership Management) to manipulate file permissions on the device.
3. Exploiting the improper file ownership, the attacker overwrites critical system files with malicious versions.
4. The attacker exploits CVE-2026-3868 (Improper Handling of Length Parameter Inconsistency) to trigger a buffer overflow.
5. The buffer overflow allows the attacker to inject arbitrary code into the running system process.
6. The injected code provides the attacker with a reverse shell to the device with elevated privileges.
7. The attacker uses the reverse shell to gain full control over the router, modifying configurations and potentially disrupting network operations.
8. Finally, the attacker pivots to other devices on the network, using the compromised router as a launchpad for further attacks within the industrial control system (ICS) network.

Impact

Successful exploitation of these vulnerabilities could allow unauthorized access and control of the affected Moxa routers. In industrial environments, this can lead to disruption of critical services, manipulation of industrial processes, and potential physical damage to equipment. Given the widespread use of Moxa devices in various sectors, including manufacturing, transportation, and energy, a successful attack could have significant consequences. The impact would vary depending on the specific industrial process controlled by the affected router, but could potentially affect dozens of organizations and even critical infrastructure.

Recommendation

• Immediately patch all affected Moxa devices (TN-4900, EDR-8010, EDR-G9010, OnCell G4302-LTE4, OnCell G4308-LTE4, and EDF-G1002-BP Series) to the latest firmware versions as recommended in the Moxa security advisory.
• Monitor network traffic for unusual patterns or connections originating from Moxa routers, indicative of potential exploitation, by deploying the “Detect Suspicious Outbound Connection from Moxa Router” Sigma rule.
• Implement strict access control policies to limit access to Moxa devices and segment the network to prevent lateral movement in case of a compromise.