CVE-2017-6032 in Modicon Modbus Protocol
Summary
by MITRE
A Violation of Secure Design Principles issue was discovered in Schneider Electric Modicon Modbus Protocol. The Modicon Modbus protocol has a session-related weakness making it susceptible to brute-force attacks.
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Analysis
by VulDB Data Team • 12/30/2020
The vulnerability identified as CVE-2017-6032 represents a critical flaw in Schneider Electric's Modicon Modbus Protocol implementation that fundamentally violates secure design principles. This issue stems from inadequate session management and authentication mechanisms within the Modbus protocol implementation, creating a significant security weakness that exposes industrial control systems to targeted attacks. The Modicon Modbus protocol, widely deployed in industrial environments for communication between programmable logic controllers and other devices, suffers from a design oversight that fails to properly enforce access controls and session integrity measures.
The technical flaw manifests as a vulnerability in the protocol's session handling mechanism that allows attackers to perform brute-force authentication attempts without effective rate limiting or account lockout mechanisms. This weakness enables malicious actors to systematically guess valid credentials through automated tools, exploiting the protocol's failure to implement proper authentication throttling. The vulnerability specifically affects the Modicon Modbus protocol implementation where session tokens or authentication mechanisms do not adequately protect against repeated login attempts, creating a pathway for unauthorized access to industrial control systems. This design flaw directly relates to CWE-307 - Improper Restriction of Excessive Authentication Attempts, which addresses insufficient protections against automated authentication attacks.
The operational impact of this vulnerability extends beyond simple credential guessing, as successful exploitation can lead to complete system compromise of industrial control infrastructure. Attackers who gain unauthorized access through brute-force methods can manipulate industrial processes, potentially causing production disruptions, safety hazards, or even physical damage to equipment. The Modicon Modbus protocol is commonly used in critical infrastructure sectors including power generation, water treatment, and manufacturing, where unauthorized access could result in significant financial losses, environmental damage, or public safety risks. This vulnerability particularly affects environments where industrial networks lack proper network segmentation or additional security controls, amplifying the potential damage from successful exploitation.
Organizations should implement multiple layers of defense to mitigate this vulnerability, starting with immediate deployment of authentication rate limiting mechanisms and account lockout policies on affected Modicon devices. Network segmentation and access control lists should be configured to limit direct access to Modbus protocol endpoints from untrusted networks, following the principle of least privilege as outlined in the MITRE ATT&CK framework for industrial control systems. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar design flaws in industrial protocols, with particular attention to implementing proper session management and authentication controls. System administrators should also consider deploying intrusion detection systems that can monitor for unusual authentication patterns and alert on potential brute-force attack attempts, ensuring that security monitoring capabilities are aligned with the specific threat landscape of industrial environments.