CVE-2022-29958 in TOYOPUC PLC
Summary
by MITRE • 07/27/2022
JTEKT TOYOPUC PLCs through 2022-04-29 do not ensure data integrity. They utilize the unauthenticated CMPLink/TCP protocol for engineering purposes, including downloading projects and control logic to the PLC. Control logic is downloaded to the PLC on a block-by-block basis with a given memory address and a blob of machine code. The logic that is downloaded to the PLC is not cryptographically authenticated, allowing an attacker to execute arbitrary machine code on the PLC's CPU module in the context of the runtime. In the case of the PC10G-CPU, and likely for other CPU modules of the TOYOPUC family, a processor without MPU or MMU is used and this no memory protection or privilege-separation capabilities are available, giving an attacker full control over the CPU.
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Analysis
by VulDB Data Team • 08/27/2022
CVE-2022-29958 represents a critical vulnerability in JTEKT TOYOPUC PLCs that fundamentally compromises the integrity and security of industrial control systems. This vulnerability stems from the improper implementation of the CMPLink/TCP protocol, which is used for engineering operations including project downloads and control logic transfers to the PLC. The protocol operates without authentication mechanisms, creating an attack surface where malicious actors can manipulate the system's operational behavior. The vulnerability manifests when control logic is downloaded to the PLC in block-by-block format, with each block containing a memory address and associated machine code blob. The absence of cryptographic authentication for these downloads allows attackers to inject arbitrary machine code directly into the PLC's CPU module, effectively executing malicious instructions within the runtime context of the control system.
The technical flaw in this vulnerability aligns with CWE-310, which addresses cryptographic weaknesses, and specifically relates to the lack of authentication and integrity protection in communication protocols. The vulnerability exploits the fundamental architecture of the affected PLCs, which utilize processors without Memory Protection Units or Memory Management Units, eliminating any form of memory protection or privilege separation capabilities. This architectural limitation means that any code executed on the CPU operates with full system privileges, providing attackers with complete control over the device's operations. The vulnerability affects PLCs up to the 2022-04-29 version, indicating a prolonged period during which this security gap existed without proper mitigation.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally undermines the integrity of industrial control systems that rely on these devices for critical operations. An attacker with access to the network segment can manipulate control logic in real-time, potentially causing equipment malfunctions, production disruptions, or even safety hazards in industrial environments. The lack of memory protection means that malicious code can overwrite critical system components, disable safety mechanisms, or redirect operational parameters without detection. This vulnerability particularly affects the PC10G-CPU and likely other models in the TOYOPUC family, creating a widespread risk across industrial installations that depend on these specific PLC implementations. The vulnerability's exploitation can lead to cascading failures in industrial processes, where unauthorized modifications to control logic can propagate through connected systems, potentially causing significant financial and operational damage.
Mitigation strategies for CVE-2022-29958 must address both the immediate security gap and the underlying architectural limitations of the affected PLCs. Organizations should implement network segmentation and access controls to limit physical and logical access to PLC engineering interfaces, ensuring that only authorized personnel can interact with the CMPLink/TCP protocol. Network monitoring should be enhanced to detect unusual communication patterns that may indicate unauthorized code downloads or manipulation attempts. The implementation of secure communication protocols with authentication and encryption mechanisms should be considered as a replacement for the vulnerable CMPLink/TCP protocol. Additionally, regular firmware updates should be applied when available, though the vulnerability's nature suggests that architectural changes may be necessary for complete protection. Security awareness training for industrial control system operators should emphasize the risks associated with unauthenticated network access and the importance of maintaining secure engineering environments. The vulnerability also highlights the need for industrial cybersecurity frameworks that address the specific challenges of legacy industrial systems lacking modern security features, potentially requiring a combination of network-level protections, physical security measures, and operational controls to effectively mitigate the risk.