CVE-2017-16718 in TwinCAT
Summary
by MITRE
Beckhoff TwinCAT 3 supports communication over ADS. ADS is a protocol for industrial automation in protected environments. This protocol uses user configured routes, that can be edited remotely via ADS. This special command supports encrypted authentication with username/password. The encryption uses a fixed key, that could be extracted by an attacker. Precondition of the exploitation of this weakness is network access at the moment a route is added.
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Analysis
by VulDB Data Team • 02/22/2020
The vulnerability CVE-2017-16718 affects Beckhoff TwinCAT 3 industrial automation software, specifically targeting the ADS (Automation Device Specification) protocol implementation. This protocol serves as a communication framework for industrial control systems and is designed to operate within protected environments where security is paramount. The ADS protocol supports remote route configuration capabilities that enable administrators to modify network paths and communication settings from distant locations. The authentication mechanism within this protocol relies on username/password credentials combined with encryption for secure communication.
The core technical flaw resides in the implementation of encryption within the ADS protocol's authentication process. The vulnerability stems from the use of a fixed encryption key that is embedded within the software implementation, making it vulnerable to extraction by attackers who gain network access. This weakness specifically manifests when an attacker can intercept network traffic during the route addition process, which is a critical operational moment where authentication credentials are transmitted. The fixed key approach violates fundamental security principles and represents a classic example of hard-coded cryptographic material that should never be present in production systems.
The operational impact of this vulnerability is severe within industrial control environments where TwinCAT 3 systems are deployed. An attacker who gains network access during route configuration can extract the fixed encryption key and subsequently impersonate legitimate users. This allows unauthorized individuals to modify network routes, potentially disrupting industrial processes or gaining unauthorized access to critical control systems. The vulnerability's exploitation requires only network access at the precise moment when routes are being added, making it particularly dangerous as it can be exploited during normal operational activities without requiring physical access to the system.
The security implications extend beyond simple credential theft, as this vulnerability enables attackers to manipulate the communication topology of industrial control networks. This aligns with ATT&CK technique T1071.004 for application layer protocol usage and CWE-327 for use of a broken or weak cryptographic algorithm. The fixed key vulnerability represents a critical design flaw that undermines the entire security model of the authentication system. Organizations implementing TwinCAT 3 systems must recognize that this vulnerability can enable lateral movement within industrial networks and potentially facilitate more sophisticated attacks targeting operational technology infrastructure. The impact is particularly concerning given that industrial control systems often operate in environments where network monitoring and security controls may be less sophisticated than in traditional enterprise environments.
Mitigation strategies should focus on network segmentation and access controls to prevent unauthorized network access during critical configuration operations. The recommended approach includes implementing strict network access controls, monitoring for suspicious network activity during route configuration, and applying network-level protections such as firewalls and intrusion detection systems. Additionally, organizations should consider implementing network traffic analysis to detect anomalous patterns associated with route modification attempts. The most effective long-term solution involves updating to patched versions of TwinCAT 3 that address the fixed key vulnerability and implement proper cryptographic key management practices. Security monitoring should specifically focus on identifying attempts to modify network routes and unauthorized access to ADS protocol communication channels.