Honeywell Experion PKS Safety Manager (SM and FSC) through 2022-05-06 has Insufficient Verification of Data Authenticity. According to FSCT-2022-0053, there is a Honeywell Experion PKS Safety Manager insufficient logic security controls issue. The affected components are characterized as: Honeywell FSC runtime (FSC-CPU, QPP), Honeywell Safety Builder. The potential impact is: Remote Code Execution, Denial of Service. The Honeywell Experion PKS Safety Manager family of safety controllers utilize the unauthenticated Safety Builder protocol (FSCT-2022-0051) for engineering purposes, including downloading projects and control logic to the controller. Control logic is downloaded to the controller on a block-by-block basis. The logic that is downloaded consists of FLD code compiled to native machine code for the CPU module (which applies to both the Safety Manager and FSC families). Since this logic does not seem to be cryptographically authenticated, it allows an attacker capable of triggering a logic download to execute arbitrary machine code on the controller's CPU module in the context of the runtime. While the researchers could not verify this in detail, the researchers believe that the microprocessor underpinning the FSC and Safety Manager CPU modules is incapable of offering memory protection or privilege separation capabilities which would give an attacker full control of the CPU module. There is no authentication on control logic downloaded to the controller. Memory protection and privilege separation capabilities for the runtime are possibly lacking. The researchers confirmed the issues in question on Safety Manager R145.1 and R152.2 but suspect the issue affects all FSC and SM controllers and associated Safety Builder versions regardless of software or firmware revision. An attacker who can communicate with a Safety Manager controller via the Safety Builder protocol can execute arbitrary code without restrictions on the CPU module, allowing for covert manipulation of control operations and implanting capabilities similar to the TRITON malware (MITRE ATT&CK software ID S1009). A mitigating factor with regards to some, but not all, of the above functionality is that these require the Safety Manager physical keyswitch to be in the right position.
Published July 28, 2022.