CVE-2020-7540 in Modicon M340
Summary
by MITRE • 12/11/2020
A CWE-306: Missing Authentication for Critical Function vulnerability exists in the Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions), that could cause unauthenticated command execution in the controller when sending special HTTP requests.
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Analysis
by VulDB Data Team • 12/16/2020
The vulnerability identified as CVE-2020-7540 represents a critical authentication flaw classified under CWE-306, which specifically addresses missing authentication for critical functions within software systems. This weakness manifests in the web server component of several Modicon industrial control devices including the M340 series, Legacy Offers Modicon Quantum, Modicon Premium, and their associated communication modules. The affected systems operate within industrial control environments where unauthorized access can have severe operational and security implications.
The technical exploitation of this vulnerability occurs through specially crafted HTTP requests that bypass the normal authentication mechanisms required for accessing critical controller functions. When these malicious requests are sent to the vulnerable web server, they can trigger unauthenticated command execution directly on the controller itself. This flaw essentially allows attackers to perform administrative operations without proper credentials, potentially enabling them to modify system configurations, access sensitive data, or disrupt operational processes.
From an operational impact perspective, this vulnerability poses significant risks to industrial environments where Modicon controllers are deployed. The ability to execute commands without authentication creates opportunities for attackers to compromise the integrity of industrial control systems, potentially leading to production disruptions, safety hazards, or unauthorized access to critical infrastructure. The vulnerability affects multiple generations of Modicon products, indicating a widespread exposure across different industrial control platforms that organizations may not have fully addressed.
Organizations should implement immediate mitigations including network segmentation to isolate affected devices from general network access, applying manufacturer-provided security patches and firmware updates, and implementing network monitoring to detect suspicious HTTP traffic patterns. The vulnerability aligns with ATT&CK technique T1190 for exploit public-facing application and T1071.005 for application layer protocol web protocols, making it a significant concern for industrial cybersecurity programs. Additionally, this vulnerability demonstrates the importance of implementing proper authentication controls for all critical functions within industrial control systems, as outlined in cybersecurity frameworks such as NIST SP 800-82 and IEC 62443 standards.