CVE-2019-3941 in WebAccess
Summary
by MITRE
Advantech WebAccess 8.3.4 allows unauthenticated, remote attackers to delete arbitrary files via IOCTL 10005 RPC.
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Analysis
by VulDB Data Team • 08/28/2023
The vulnerability identified as CVE-2019-3941 affects Advantech WebAccess version 8.3.4, a supervisory control and data acquisition system widely deployed in industrial environments for monitoring and control operations. This critical security flaw resides within the remote procedure call (RPC) interface of the WebAccess software, specifically through the handling of IOCTL 10005 operations. The vulnerability represents a significant weakness in the system's access controls, as it permits any remote attacker to execute arbitrary file deletion commands without requiring authentication credentials or prior access privileges. This design flaw directly violates fundamental security principles of least privilege and authentication enforcement that are essential for industrial control systems.
The technical implementation of this vulnerability stems from improper input validation and access control mechanisms within the WebAccess RPC service. When an attacker sends a malformed RPC request containing IOCTL 10005 command, the system fails to properly authenticate the requestor or validate the legitimacy of the file deletion operation. This allows attackers to specify arbitrary file paths and initiate deletion commands against any file accessible to the WebAccess service account. The vulnerability operates at the kernel level through the Windows Device I/O Control mechanism, making it particularly dangerous as it can target system-critical files, configuration data, or operational files that could compromise the entire industrial control environment. The lack of authentication requirements places this vulnerability in the CWE-287 category, which addresses improper authentication issues, while the unvalidated input handling aligns with CWE-125, representing out-of-bounds read conditions that can lead to arbitrary code execution or data manipulation.
The operational impact of this vulnerability extends far beyond simple file deletion capabilities, as it fundamentally compromises the integrity and availability of industrial control systems. Attackers could potentially target configuration files, log files, or even executable components of the WebAccess system, leading to complete system compromise or operational disruption. In industrial environments where WebAccess is used for critical infrastructure monitoring, this vulnerability could result in unauthorized modification of control parameters, data corruption, or complete system outages that could have cascading effects on production processes. The remote nature of the attack means that threat actors can exploit this vulnerability from anywhere on the network, eliminating the need for physical access or insider threats. This weakness directly maps to several ATT&CK techniques including T1059 for command and scripting interpreter, T1070 for indicator removal, and T1486 for data encryption for ransomware, as attackers could delete critical system files or encrypt data to extort victims. The vulnerability also creates opportunities for attackers to establish persistence within the system by deleting security-related files or modifying system configurations.
Organizations utilizing Advantech WebAccess 8.3.4 should immediately implement multiple layers of mitigation strategies to protect against exploitation of this vulnerability. The primary recommendation involves applying the vendor-provided security patches and updates as soon as they become available, which should address the authentication bypass and input validation flaws. Network segmentation should be implemented to isolate WebAccess systems from general network traffic, limiting the attack surface and reducing the likelihood of successful exploitation. Access controls must be strengthened through the implementation of network access control lists, firewall rules, and mandatory access controls that restrict RPC communication to trusted network segments only. Additionally, organizations should conduct comprehensive security audits of their WebAccess installations, including reviewing file permissions, monitoring RPC traffic for suspicious activity, and implementing intrusion detection systems specifically configured to identify anomalous RPC requests. System administrators should also disable unnecessary RPC services and ports, particularly those that are not essential for the operation of the WebAccess system. Regular security assessments and vulnerability scanning should be performed to identify any additional weaknesses in the industrial control environment that could be exploited in conjunction with this vulnerability. The implementation of these mitigations aligns with NIST SP 800-82 guidelines for industrial control systems security, which emphasize the importance of secure configuration management and network segmentation in protecting critical infrastructure assets.