Ethernet Vulnerabilities in Safety Instrumented Systems (SIS): A Key Difference

Dragos reported multiple undocumented security defects in Schneider Electric's Triconex Tricon Communication Module (TCM) that enable denial-of-service (CVE-2020-7486) and firmware/root compromise (CVE-2020-7491). These flaws permit attackers to fault the TCM or overwrite its firmware to stage or inject malicious logic (e.g., TRISIS) into SIS processors, and can be exploited even with the SIS keyswitch set to "Run"; recommended mitigations include blocking undocumented TCM services, restricting engineering workstation access, and monitoring for unexpected communications.