CVE-2021-25094 : Exploit Details and Defense Strategies

Tatsu WordPress plugin before version 3.3.12 is vulnerable to an unauthenticated remote code execution (RCE) exploit. The plugin allows the add_custom_font action without authentication, enabling an attacker to upload a malicious zip file that can bypass extension control and potentially execute arbitrary code on the server.

Understanding CVE-2021-25094

This section provides an overview of the vulnerability, its impact, technical details, and mitigation steps.

What is CVE-2021-25094?

The CVE-2021-25094 vulnerability in the Tatsu WordPress plugin allows an unauthenticated attacker to upload a rogue zip file, potentially leading to remote code execution on the server.

The Impact of CVE-2021-25094

The vulnerability poses a significant risk as it allows an attacker to bypass security controls and execute malicious code on the affected WordPress site, compromising its integrity and confidentiality.

Technical Details of CVE-2021-25094

This section delves into the specifics of the vulnerability, including its description, affected systems and versions, and exploitation mechanism.

Vulnerability Description

By leveraging the add_custom_font action without authentication, an attacker can upload a crafted zip file that bypasses extension control. A race condition during the zip extraction process allows the malicious file to remain on the server for an extended period, enabling remote code execution.

Affected Systems and Versions

The Tatsu WordPress plugin versions before 3.3.12 are vulnerable to this exploit. Users running versions prior to this are at risk of exploitation by threat actors.

Exploitation Mechanism

Attackers can exploit this vulnerability by uploading a specially crafted zip file with a PHP shell containing a filename starting with a dot ".". This shell file can then be invoked by the attacker, leading to unauthorized code execution.

Mitigation and Prevention

Protecting your WordPress site from CVE-2021-25094 requires immediate action and long-term security measures.

Immediate Steps to Take

Users are advised to update the Tatsu plugin to version 3.3.12 or later to mitigate the vulnerability. Additionally, restricting access to the plugin and ensuring file upload controls can help prevent unauthorized file execution.

Long-Term Security Practices

Implementing secure coding practices, regularly monitoring for suspicious activities, and conducting security audits can enhance the overall security posture of WordPress sites.

Patching and Updates

Stay informed about security patches released by the plugin vendor and apply them promptly to safeguard your WordPress installation from potential exploits.