CVE-2018-15703 in WebAccess
Summary
by MITRE
Advantech WebAccess 8.3.2 and below is vulnerable to multiple reflected cross site scripting vulnerabilities. A remote unauthenticated attacker could potentially exploit this vulnerability by tricking a victim to supply malicious HTML or JavaScript code to WebAccess, which is then reflected back to the victim and executed by the web browser.
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Analysis
by VulDB Data Team • 04/05/2020
The vulnerability identified as CVE-2018-15703 affects Advantech WebAccess versions 8.3.2 and earlier, representing a critical security flaw that exposes the industrial automation platform to cross site scripting attacks. This vulnerability resides within the web interface component of the software, which is designed to provide remote monitoring and control capabilities for industrial systems. The affected version demonstrates inadequate input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before it is processed and returned to web clients. The flaw specifically manifests as reflected cross site scripting vulnerabilities, where malicious payloads are injected through web requests and subsequently reflected back to users without proper sanitization.
The technical exploitation of this vulnerability requires an attacker to craft malicious URLs containing JavaScript code or HTML elements that are then processed by the WebAccess web server. When a victim clicks on such a crafted link or visits a malicious web page containing the exploit, the malicious code becomes part of the server response and executes within the victim's browser context. This reflected nature of the vulnerability means that the attack payload is not stored on the server but is instead reflected from the web server's response, making it particularly challenging to detect through traditional security monitoring approaches. The vulnerability affects the authentication mechanisms of the web interface, as the attack can be executed without requiring valid credentials, making it especially dangerous for industrial environments where operational technology systems are often exposed to external networks.
The operational impact of this vulnerability extends beyond simple data theft or session hijacking, as it can potentially enable more sophisticated attacks within industrial control systems. An attacker could leverage this vulnerability to manipulate the web interface, potentially gaining unauthorized access to sensitive operational data, modifying system configurations, or even executing malicious code on the industrial control system. The reflected nature of the attack allows for rapid deployment of exploits without requiring persistent access to the system, making it particularly dangerous in environments where industrial systems are connected to corporate networks. This vulnerability directly relates to CWE-79 which defines the weakness of cross site scripting in web applications, and aligns with ATT&CK technique T1212 which addresses exploitation of web application vulnerabilities for privilege escalation and data exfiltration.
Mitigation strategies for this vulnerability should include immediate patching of the Advantech WebAccess software to versions that address the cross site scripting flaws. Network segmentation should be implemented to limit direct exposure of industrial control systems to external networks, and web application firewalls should be deployed to monitor and filter malicious traffic patterns. Input validation and output encoding mechanisms within the web interface should be strengthened to ensure all user-supplied data is properly sanitized before processing. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other industrial control system components. Additionally, user education regarding phishing attacks and suspicious links should be emphasized to reduce the risk of successful social engineering attacks that exploit this vulnerability. The vulnerability also highlights the importance of implementing proper security controls for operational technology environments, as these systems often lack the robust security measures found in traditional enterprise environments.