CVE-2021-29489 : Exploit Details and Defense Strategies

Highcharts JS is a popular JavaScript charting library that is widely used for creating interactive and visually appealing charts. In versions 8 and earlier, there was a vulnerability where the chart options structure was not adequately filtered for XSS vectors. This meant that content from untrusted sources could potentially execute code in the end user's browser, posing a significant security risk.

Understanding CVE-2021-29489

This CVE identifier highlights a security issue in Highcharts versions 8 and below, where the options structure was susceptible to Cross-site Scripting (XSS) attacks.

What is CVE-2021-29489?

Highcharts versions 8 and earlier failed to systematically filter the chart options structure for XSS vectors. This vulnerability could allow attackers to inject malicious code into the options structure, leading to the execution of unauthorized scripts in users' browsers.

The Impact of CVE-2021-29489

The impact of this vulnerability is rated as HIGH due to the potential for executing malicious code in the browser. Attackers could exploit this issue to steal sensitive information, compromise user privacy, or perform other unauthorized actions.

Technical Details of CVE-2021-29489

In this section, we will delve deeper into the technical aspects of the CVE, including the vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability in Highcharts versions 8 and earlier arises from a lack of proper filtration of the chart options structure, allowing for the injection of XSS payloads.

Affected Systems and Versions

Highcharts versions prior to 9.0.0 are affected by this vulnerability. Users of these versions are advised to update to version 9 or apply the workaround mentioned below.

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting malicious scripts and injecting them into the chart options structure. Subsequently, when unsuspecting users view the charts, the malicious code gets executed in their browsers.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-29489, users and administrators can take immediate steps to enhance security and prevent potential attacks.

Immediate Steps to Take

Implementers who are unable to upgrade to Highcharts version 9 are advised to apply DOMPurify recursively to the options structure. This will help filter out any malicious markup and minimize the risk of XSS attacks.

Long-Term Security Practices

In the long term, organizations should prioritize regular software updates and security patches to ensure that their systems are protected against known vulnerabilities. Additionally, conducting security audits and implementing secure coding practices can help prevent future security issues.

Patching and Updates

The primary mitigation strategy for CVE-2021-29489 is to update to Highcharts version 9. By upgrading to the latest version, users can ensure that the vulnerability is patched, and their systems are safeguarded against potential XSS attacks.