CVE-2019-3942 in WebAccess
Summary
by MITRE
Advantech WebAccess 8.3.4 does not properly restrict an RPC call that allows unauthenticated, remote users to read files. An attacker can use this vulnerability to recover the administrator password.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/12/2024
The vulnerability identified as CVE-2019-3942 affects Advantech WebAccess version 8.3.4, a industrial automation and monitoring platform widely deployed in critical infrastructure environments. This flaw represents a significant security weakness that undermines the authentication mechanisms of the system, creating an unauthorized access vector that could lead to complete system compromise. The vulnerability stems from improper restrictions within the Remote Procedure Call (RPC) functionality, which is designed to enable remote system management and communication but has been improperly configured to accept requests without proper authentication verification.
The technical implementation of this vulnerability lies in the RPC call handling mechanism where the system fails to adequately validate incoming requests before processing them. This misconfiguration allows any remote attacker to submit RPC calls without presenting valid credentials, effectively bypassing the authentication layer that should protect sensitive system functions. The specific flaw enables attackers to read arbitrary files from the system filesystem, including configuration files and password hash databases that contain administrator credentials. This represents a classic case of insufficient access control, classified under CWE-284 which addresses improper access control in software systems. The vulnerability exists at the application layer where RPC services are exposed to external networks without proper authentication gates, creating an attack surface that directly violates fundamental security principles of layered defense.
From an operational perspective, this vulnerability presents a severe risk to industrial control systems and supervisory control and data acquisition (SCADA) environments where Advantech WebAccess is commonly deployed. The ability to recover administrator passwords provides attackers with full system privileges, enabling them to modify configurations, access sensitive operational data, and potentially disrupt industrial processes. The impact extends beyond simple credential theft as it allows for persistent access and lateral movement within network segments where these systems operate. According to ATT&CK framework, this vulnerability maps to T1078 (Valid Accounts) and T1566 (Phishing for Information) techniques, as it enables attackers to leverage compromised credentials for further system compromise. The remote nature of the exploit means that attackers can target these systems from outside the network perimeter, making traditional network-based security controls ineffective against this specific threat vector.
Mitigation strategies for CVE-2019-3942 should prioritize immediate patching of affected Advantech WebAccess installations to the latest security updates provided by the vendor. Network segmentation and firewall rules should be implemented to restrict access to RPC ports and services to only trusted administrative networks. Organizations should also implement monitoring solutions to detect unusual RPC call patterns and unauthorized file access attempts. Additionally, regular security assessments and penetration testing should be conducted to identify similar authentication bypass vulnerabilities in industrial control systems. The vulnerability highlights the critical importance of proper authentication implementation in industrial environments where system integrity and operational security are paramount, and represents a clear example of how insufficient access control mechanisms can create catastrophic security risks in critical infrastructure systems.