CVE-2021-34540 in WebAccess
Summary
by MITRE • 06/11/2021
Advantech WebAccess 8.4.2 and 8.4.4 allows XSS via the username column of the bwRoot.asp page of WADashboard.
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Analysis
by VulDB Data Team • 06/14/2021
The vulnerability identified as CVE-2021-34540 affects Advantech WebAccess versions 8.4.2 and 8.4.4, specifically targeting the WADashboard component where cross-site scripting attacks can be executed through the username column of the bwRoot.asp page. This represents a critical security flaw that undermines the integrity of the web-based industrial automation platform. The vulnerability stems from inadequate input validation and output encoding mechanisms within the web interface, allowing malicious actors to inject malicious scripts into user sessions. The affected WebAccess platform serves industrial control systems and monitoring environments, making this vulnerability particularly concerning for operational technology infrastructure. The username column in the bwRoot.asp page fails to properly sanitize user-supplied input, creating an attack surface where malicious payloads can be executed within the context of authenticated user sessions. This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and demonstrates how insufficient sanitization of user-controllable data can lead to unauthorized code execution. The attack vector leverages the fact that user-provided data flows directly into the web page output without proper context-aware encoding, enabling attackers to inject script tags or other malicious content that executes in the victim's browser.
The operational impact of this vulnerability extends beyond typical web application security concerns due to the industrial nature of Advantech WebAccess deployments. When exploited, the XSS vulnerability can enable attackers to hijack user sessions, steal authentication credentials, or perform actions on behalf of authenticated users within the industrial control environment. The consequences are particularly severe in industrial settings where WebAccess platforms manage critical infrastructure monitoring and control systems. Attackers could potentially manipulate the displayed user information to redirect users to malicious sites or inject phishing content that appears legitimate within the trusted WebAccess interface. The vulnerability affects the authentication and authorization mechanisms of the platform, potentially allowing unauthorized access to sensitive operational data and control functions. This type of vulnerability creates opportunities for attackers to establish persistent access within industrial networks, as the compromised session could provide access to additional system resources or facilitate lateral movement. The impact is amplified by the fact that industrial environments often lack the sophisticated security monitoring and incident response capabilities found in traditional enterprise environments, making such attacks harder to detect and mitigate.
Mitigation strategies for CVE-2021-34540 should focus on immediate patching of affected Advantech WebAccess versions, as well as implementing comprehensive input validation and output encoding controls. Organizations should deploy web application firewalls to filter malicious content before it reaches the vulnerable application components, while also implementing strict content security policies to prevent script execution in the browser context. The remediation process must include comprehensive testing to ensure that all user-supplied data flows through proper sanitization mechanisms before being rendered in web interfaces. Network segmentation and access controls should be strengthened to limit the potential impact of successful exploitation, particularly in industrial environments where the attack surface is already constrained. Security monitoring should be enhanced to detect anomalous behavior patterns that might indicate exploitation attempts, including unusual data flows or access patterns within the WebAccess dashboard. Additionally, regular security assessments should be conducted to identify similar vulnerabilities in other industrial control system components, as the underlying architectural issues that enable this XSS vulnerability are commonly found in industrial web applications. The remediation approach should align with NIST SP 800-53 security controls and follow the ATT&CK framework's methodology for identifying and mitigating web application threats. Organizations must also consider implementing multi-factor authentication and privileged access management solutions to reduce the impact of session hijacking attacks that could result from successful exploitation of this vulnerability.