CVE-2020-7565

Vulnerability

A CWE-326 Inadequate Encryption Strength vulnerability exists in Schneider Electric Modicon M221 programmable logic controllers (all references, all versions). The encryption between EcoStruxure Machine - Basic software and the controller is weak, allowing an attacker who captures network traffic to break the encryption key [1].

Exploitation

An attacker on an adjacent network can capture traffic between the software and the controller. The attack requires user interaction (the user must be actively using the software) and has high complexity, as indicated by the CVSS vector (AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H). By analyzing captured encrypted communication, the attacker can recover the encryption key [1].

Impact

Successful exploitation allows the attacker to gain unauthorized access to the PLC, take control, and expose sensitive information. The CVSS score of 7.1 reflects high impacts on confidentiality, integrity, and availability. The attacker could decrypt all subsequent communications and potentially manipulate the controller [1].

Mitigation

As of the advisory publication date (November 2020), no firmware fix has been released. Mitigations include restricting network access to the controller via segmentation and firewall rules, using strong authentication, and following security best practices outlined in the CISA advisory [1]. Users should monitor Schneider Electric for future updates.