CVE-2020-7541 in Modicon M340
Summary
by MITRE • 12/11/2020
A CWE-425: Direct Request ('Forced Browsing') 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 disclosure of sensitive data when sending a specially crafted request to the controller over HTTP.
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Analysis
by VulDB Data Team • 12/16/2020
The vulnerability identified as CVE-2020-7541 represents a critical security flaw classified under CWE-425, which specifically addresses direct request or forced browsing vulnerabilities in web applications. This weakness manifests within the web server component of several Modicon PLC platforms including the M340 series, Legacy Offers Modicon Quantum, and Modicon Premium along with their associated communication modules. The vulnerability stems from insufficient access controls that allow unauthorized users to bypass normal authentication mechanisms and directly access protected resources through crafted HTTP requests.
The technical implementation of this vulnerability enables attackers to exploit the web server's lack of proper authorization checks by constructing specific HTTP requests that directly target sensitive system files or directories. This flaw operates at the application layer where the web server fails to properly validate incoming requests before granting access to restricted resources. The affected systems typically serve web interfaces for configuration and monitoring purposes, making them prime targets for information disclosure attacks that could expose operational data, system configurations, or other sensitive information.
The operational impact of this vulnerability extends beyond simple data exposure, as it can provide attackers with comprehensive insights into industrial control system architecture and operational parameters. When exploited, the vulnerability allows unauthorized access to sensitive data that may include system credentials, configuration files, operational parameters, and potentially business-critical information. This exposure can compromise the integrity and confidentiality of industrial processes, potentially enabling more sophisticated attacks such as those targeting the availability of critical systems or facilitating lateral movement within industrial networks.
Organizations utilizing affected Modicon PLC platforms should implement immediate mitigations including network segmentation to isolate these devices from general network access, deployment of web application firewalls to filter malicious requests, and implementation of proper access controls and authentication mechanisms. The vulnerability aligns with ATT&CK technique T1071.001 for application layer protocol usage and T1068 for exploit for privilege escalation, making it particularly dangerous in industrial environments where operational technology security is paramount. Regular security assessments and firmware updates should be prioritized to address this weakness, as the vulnerability affects legacy systems that may not receive regular security patches. Additionally, network monitoring should be enhanced to detect unusual HTTP request patterns that could indicate exploitation attempts, and access logs should be reviewed regularly for unauthorized access attempts to web interfaces.