CVE-2021-21809 : Exploit Details and Defense Strategies

A command execution vulnerability exists in the default legacy spellchecker plugin in Moodle 3.10 that allows for unauthorized command execution by sending crafted HTTP requests. This vulnerability requires an attacker to have administrator privileges to exploit it.

Understanding CVE-2021-21809

This section provides an overview of the CVE-2021-21809 vulnerability in Moodle 3.10.

What is CVE-2021-21809?

CVE-2021-21809 is an OS command injection vulnerability in the default legacy spellchecker plugin of Moodle version 3.10. It allows attackers with administrator privileges to execute commands through specially crafted HTTP requests.

The Impact of CVE-2021-21809

With a CVSS base score of 8.2 (High severity), this vulnerability poses a significant threat to confidentiality, potentially leading to unauthorized access and sensitive data exposure.

Technical Details of CVE-2021-21809

This section dives into the technical aspects of CVE-2021-21809 in Moodle 3.10.

Vulnerability Description

The vulnerability arises from improper input validation in the spellchecker plugin, enabling attackers to inject and execute arbitrary OS commands.

Affected Systems and Versions

Moodle version 3.10 is specifically affected by this vulnerability due to the presence of the default legacy spellchecker plugin.

Exploitation Mechanism

Exploiting this vulnerability involves sending a series of crafted HTTP requests to the spellchecker plugin while possessing administrator privileges.

Mitigation and Prevention

Learn how to protect your systems and prevent exploitation of CVE-2021-21809 in Moodle 3.10.

Immediate Steps to Take

Administrators should disable the legacy spellchecker plugin and implement strict access controls to mitigate the risk of command execution.

Long-Term Security Practices

Regular security audits, user training on safe practices, and consistent monitoring of Moodle installations are essential for maintaining a secure environment.

Patching and Updates

Keep Moodle up to date with the latest security patches and version upgrades to address known vulnerabilities and enhance overall system security.