CVE-2019-6549 in PR100088 Modbus Gateway
Summary
by MITRE
An attacker could retrieve plain-text credentials stored in a XML file on PR100088 Modbus gateway versions prior to Release R02 (or Software Version 1.1.13166) through FTP.
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Analysis
by VulDB Data Team • 05/09/2020
The vulnerability identified as CVE-2019-6549 represents a critical security flaw in PR100088 Modbus gateway devices manufactured by a specific vendor. This issue affects firmware versions prior to Release R02, which corresponds to Software Version 1.1.13166, creating a significant exposure window for affected systems. The vulnerability stems from improper handling of credential storage within XML configuration files, where sensitive authentication information is stored in plain text format rather than being adequately protected or encrypted. This weakness directly violates fundamental security principles regarding credential management and data protection.
The technical implementation of this vulnerability involves the Modbus gateway's configuration file handling mechanism where user credentials are serialized into XML format without proper encryption or obfuscation. When the device communicates via FTP protocol, these XML files containing plain-text credentials become accessible to unauthorized parties who may exploit the FTP service to retrieve the configuration data. The flaw demonstrates poor secure coding practices and inadequate security controls in the device's configuration management system, creating an attack surface that allows for credential theft through network-based reconnaissance and exploitation. This vulnerability falls under CWE-312 (Cleartext Storage of Sensitive Information) and represents a classic example of insecure data storage practices that have been repeatedly identified in industrial control systems and IoT devices.
From an operational perspective, this vulnerability presents a severe risk to industrial environments that rely on Modbus gateways for communication between different network segments. Attackers who can access the FTP service of affected devices can easily extract authentication credentials and potentially escalate their privileges to gain full administrative control over the gateway. The impact extends beyond the immediate device, as compromised credentials may be reused across other systems within the network infrastructure, leading to lateral movement and broader security breaches. The vulnerability is particularly concerning in industrial settings where these gateways often serve as critical communication bridges between operational technology and information technology systems, making them prime targets for sophisticated attacks. This flaw aligns with ATT&CK technique T1078 (Valid Accounts) and T1566 (Phishing for Information) as attackers can leverage the stolen credentials to establish persistent access and conduct reconnaissance activities.
The recommended mitigation strategies for CVE-2019-6549 involve immediate firmware updates to Release R02 or later versions that address the credential storage vulnerability. Organizations should also implement network segmentation to limit FTP access to only authorized personnel and systems, while conducting thorough inventory assessments to identify all affected Modbus gateway devices within their infrastructure. Additional protective measures include implementing network monitoring to detect unauthorized FTP access attempts, enforcing strong authentication mechanisms for FTP services, and establishing regular security audits of configuration files to ensure proper credential handling. The vulnerability highlights the importance of secure configuration management practices and proper credential lifecycle management in industrial environments, emphasizing the need for comprehensive security controls that address both network and application-level threats.