CVE-2018-7824 in Modbus Serial Driver
Summary
by MITRE
An Externally Controlled Reference to a Resource (CWE-610) vulnerability exists in Schneider Electric Modbus Serial Driver (For 64-bit Windows OS:V3.17 IE 37 and prior , For 32-bit Windows OS:V2.17 IE 27 and prior, and as part of the Driver Suite version:V14.12 and prior) which could allow write access to system files available only to users with SYSTEM privilege or other important user files.
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Analysis
by VulDB Data Team • 06/14/2020
The vulnerability described in CVE-2018-7824 represents a critical security flaw in Schneider Electric's Modbus Serial Driver software that falls under the category of externally controlled reference to a resource as classified by CWE-610. This weakness occurs when an application uses external input to construct file paths or resource references without proper validation, creating an avenue for attackers to manipulate the system's resource access patterns. The affected versions include specific 64-bit and 32-bit Windows implementations with the 64-bit version being vulnerable up to V3.17 IE 37 and the 32-bit version up to V2.17 IE 27, while also encompassing the broader Driver Suite version V14.12 and prior. The vulnerability specifically affects systems running on Windows operating systems where the Modbus Serial Driver is installed, making it particularly concerning for industrial control systems and automation environments where Schneider Electric products are commonly deployed.
The technical implementation of this vulnerability allows an attacker to gain unauthorized write access to system files that are typically restricted to users with SYSTEM privileges or other critical user files. This occurs because the driver fails to properly validate external inputs used in file reference construction, enabling malicious actors to redirect file operations to unintended locations. The flaw essentially creates a path traversal or resource manipulation scenario where external parameters can influence the target of file operations, potentially allowing attackers to modify critical system components or inject malicious code into the driver environment. This type of vulnerability directly impacts the principle of least privilege and can lead to privilege escalation scenarios where standard user accounts can potentially gain system-level access through manipulation of the driver's file handling mechanisms.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it creates opportunities for attackers to compromise the integrity and availability of industrial control systems that rely on Schneider Electric Modbus Serial Drivers. The affected systems could include manufacturing environments, power grid control systems, and other critical infrastructure where Modbus communication protocols are utilized for device control and monitoring. Attackers could potentially modify driver executables, configuration files, or system binaries to establish persistence, disable security features, or redirect communication flows to malicious endpoints. This vulnerability is particularly dangerous in industrial environments where system stability and security are paramount, as unauthorized modifications could lead to operational disruptions, safety hazards, or data integrity compromises that affect entire production facilities.
Organizations should implement immediate mitigation strategies including applying the latest patches and updates provided by Schneider Electric to address the vulnerability in affected driver versions. System administrators should conduct comprehensive inventory assessments to identify all installations of the vulnerable Modbus Serial Driver software across their networks and ensure proper access controls are implemented to limit user privileges. Network segmentation and monitoring should be enhanced to detect unusual file access patterns or modifications that could indicate exploitation attempts. The vulnerability aligns with several ATT&CK techniques including privilege escalation through exploitation of software vulnerabilities and persistence mechanisms that leverage modified system files. Additionally, organizations should consider implementing application whitelisting policies and ensuring that only authorized users have access to systems where the vulnerable drivers are installed, as this represents a fundamental weakness in the software's input validation and resource access control mechanisms.