CVE-2021-22749 in Modicon X80 BMXNOR0200H RTU
Summary
by MITRE • 06/11/2021
A CWE-200: Exposure of Sensitive Information to an Unauthorized Actor vulnerability exists in Modicon X80 BMXNOR0200H RTU SV1.70 IR22 and prior that could cause information leak concerning the current RTU configuration including communication parameters dedicated to telemetry, when a specially crafted HTTP request is sent to the web server of the module.
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Analysis
by VulDB Data Team • 06/14/2021
The vulnerability identified as CVE-2021-22749 represents a critical exposure of sensitive information within industrial control systems, specifically targeting the Modicon X80 BMXNOR0200H RTU firmware version 1.70 and earlier. This weakness falls under CWE-200, which categorizes the improper exposure of sensitive information to unauthorized actors, making it particularly dangerous in industrial environments where operational technology security is paramount. The affected device operates as a remote terminal unit within industrial automation systems, serving as a crucial interface for telemetry data collection and communication with central control systems.
The technical flaw manifests through the web server implementation within the RTU's firmware, which fails to properly validate or sanitize incoming HTTP requests. When an attacker crafts a specific HTTP request and sends it to the vulnerable web server, the system responds by disclosing sensitive configuration details including communication parameters that are typically restricted to authorized personnel only. This information leakage occurs because the web server lacks adequate access controls or input validation mechanisms to prevent unauthorized data retrieval from internal system components.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked configuration data could enable sophisticated attackers to gain deeper insights into the industrial control system architecture. The exposed telemetry communication parameters may include network addresses, port configurations, authentication credentials, or protocol specifications that could be leveraged for further attacks. This vulnerability particularly affects the security posture of industrial environments where these RTUs serve as critical nodes in SCADA systems, potentially enabling attackers to map network topologies, identify communication protocols, or develop targeted attacks against other system components.
Security professionals should recognize this vulnerability as a potential entry point for attackers following the MITRE ATT&CK framework's methodology for lateral movement and reconnaissance activities. The disclosure of communication parameters aligns with techniques used in initial access and reconnaissance phases, where adversaries gather intelligence about system configurations to plan more sophisticated attacks. Organizations implementing industrial control systems should consider this vulnerability as part of their broader security assessment, particularly when evaluating the security of legacy devices that may not receive regular firmware updates or security patches.
Mitigation strategies should prioritize immediate firmware updates from the vendor to address the root cause of the vulnerability, while also implementing network segmentation to limit access to these critical devices. Additional protective measures include deploying web application firewalls to filter suspicious HTTP requests, implementing strict access controls for web server interfaces, and conducting regular security assessments to identify similar vulnerabilities in other industrial control system components. The vulnerability underscores the importance of maintaining up-to-date firmware in industrial environments and demonstrates how seemingly minor implementation flaws can create significant security risks in critical infrastructure systems.