CVE-2021-37936 Explained : Impact and Mitigation

A security vulnerability has been identified in Kibana versions before 7.14.1 that could allow an attacker to inject HTML snippets into the Elasticsearch index. This could result in the execution of malicious code when the Discover app renders search terms.

Understanding CVE-2021-37936

Kibana, a data visualization dashboard for Elasticsearch, was found to lack proper sanitization of document fields containing HTML snippets, leading to a potential HTML injection attack.

What is CVE-2021-37936?

CVE-2021-37936 is a vulnerability in Kibana that allows an attacker to insert HTML code into document fields, exploiting the lack of sanitization and potentially executing malicious scripts.

The Impact of CVE-2021-37936

If exploited, this vulnerability could enable an attacker to inject harmful HTML code into the Elasticsearch index. When the Discover app retrieves and displays search results containing the injected HTML, it could lead to cross-site scripting (XSS) attacks.

Technical Details of CVE-2021-37936

The following section provides more insight into the specific technical aspects of the CVE-2021-37936 vulnerability.

Vulnerability Description

The vulnerability arises from Kibana's failure to properly sanitize document fields storing HTML snippets, allowing an attacker to insert malicious code.

Affected Systems and Versions

Elastic's Kibana versions before 7.14.1 are impacted by this security flaw. Users running these versions are at risk of HTML injection attacks.

Exploitation Mechanism

Attackers can exploit this vulnerability by writing documents to the Elasticsearch index containing HTML code. When the Discover app highlights a search term with the injected HTML, it gets rendered, potentially triggering XSS attacks.

Mitigation and Prevention

To safeguard systems from the CVE-2021-37936 vulnerability, certain immediate steps can be taken, along with adopting long-term security measures and staying updated on relevant patches.

Immediate Steps to Take

Upgrade Kibana to version 7.14.1 or later to address the HTML injection vulnerability.
Monitor Elasticsearch and Kibana logs for any suspicious activities indicating exploitation attempts.

Long-Term Security Practices

Implement input validation mechanisms to ensure user-generated content does not contain malicious scripts.
Conduct regular security audits and penetration testing to identify and mitigate vulnerabilities proactively.

Patching and Updates

Stay informed about security advisories and updates from Elastic to promptly apply patches that address known vulnerabilities.