CVE-2021-29439 : Exploit Details and Defense Strategies

This article provides detailed information about CVE-2021-29439, a vulnerability in the Grav admin plugin that allows the installation of plugins with minimal admin privileges.

Understanding CVE-2021-29439

This section explains the impact, technical details, and mitigation strategies related to CVE-2021-29439.

What is CVE-2021-29439?

The Grav admin plugin before version 1.10.11 fails to verify caller's privileges correctly. This allows users with the

admin.login

permission to install third-party plugins and their dependencies. An attacker could exploit this to execute arbitrary code and elevate their privileges on the instance.

The Impact of CVE-2021-29439

The vulnerability poses a high risk as it enables attackers to gain unauthorized access, execute malicious code, and escalate privileges on affected instances.

Technical Details of CVE-2021-29439

This section provides insights into the vulnerability description, affected systems, and exploitation mechanism.

Vulnerability Description

The vulnerability in the Grav admin plugin (pre-version 1.10.11) allows users with 'admin.login' permission to install third-party plugins, potentially leading to arbitrary code execution and privilege escalation.

Affected Systems and Versions

The vulnerability affects the Grav-plugin-admin versions prior to 1.10.11, leaving instances vulnerable to privilege escalation and arbitrary code execution.

Exploitation Mechanism

Attackers can exploit this vulnerability by leveraging the insufficient privilege validation in the plugin to install malicious plugins and execute arbitrary code.

Mitigation and Prevention

This section outlines immediate steps to take and long-term security practices to protect systems from CVE-2021-29439.

Immediate Steps to Take

Updating the Grav admin plugin to version 1.10.11 is crucial for remediation. Additionally, blocking access to the '/admin' path from untrusted sources can reduce the risk of exploitation.

Long-Term Security Practices

Implement robust privilege verification mechanisms, monitor plugin installations, and regularly update plugins and dependencies to prevent similar vulnerabilities.

Patching and Updates

Regularly check for security updates, apply patches promptly, and follow best practices for securing admin privileges to mitigate the risk of exploitation.