CVE-2021-21803 : Security Advisory and Response

This CVE-2021-21803 article provides an overview and insights into a critical security vulnerability present in the Advantech R-SeeNet web applications.

Understanding CVE-2021-21803

CVE-2021-21803 is a high-severity vulnerability found in the device_graph_page.php script of Advantech R-SeeNet web applications. It allows an attacker to execute arbitrary JavaScript code by tricking a victim into visiting a specially crafted URL.

What is CVE-2021-21803?

This vulnerability is a result of improper neutralization of input during web page generation, specifically a 'Cross-site Scripting' (XSS) flaw. It impacts Advantech R-SeeNet version 2.4.12 (20.10.2020).

The Impact of CVE-2021-21803

With a CVSS base score of 9.6 (Critical), CVE-2021-21803 poses a significant risk. An attacker can exploit this flaw remotely without any privileges, compromising confidentiality, integrity, and availability of the affected system.

Technical Details of CVE-2021-21803

The vulnerability arises from inadequate input validation in the device_graph_page.php script.

Vulnerability Description

By crafting a malicious URL and enticing a user to click on it, an attacker can inject and execute arbitrary JavaScript code in the victim's browser, leading to various attacks.

Affected Systems and Versions

Advantech R-SeeNet version 2.4.12 (20.10.2020) is confirmed to be impacted by this vulnerability.

Exploitation Mechanism

The attacker can host a specially crafted webpage or URL, and when the victim clicks on it, the malicious code gets executed in their browser, giving the attacker unauthorized access.

Mitigation and Prevention

Organizations can follow these steps to mitigate the risks associated with CVE-2021-21803.

Immediate Steps to Take

Update the Advantech R-SeeNet application to a patched version that addresses the XSS vulnerability.
Educate users about the risks of clicking on suspicious links.

Long-Term Security Practices

Regularly scan web applications for vulnerabilities using security tools.
Implement input validation mechanisms to prevent XSS attacks.

Patching and Updates

Advantech has released a patched version addressing CVE-2021-21803. Ensure all systems are updated to the latest secure version.