CVE-2023-34252 : Vulnerability Insights and Analysis

A detailed analysis of the CVE-2023-34252 vulnerability affecting Grav server-side template injection via insufficient validation in filterFilter.

Understanding CVE-2023-34252

This CVE represents a vulnerability in Grav, a flat-file content management system, that allows attackers to perform server-side template injection due to insufficient validation mechanisms.

What is CVE-2023-34252?

Grav versions prior to 1.7.42 are affected by a logic flaw in the

GravExtension.filterFilter()

function, enabling attackers to inject malicious templates and potentially execute remote code. This vulnerability arises from a failure to properly validate unsafe functions when passed as array arguments.

The Impact of CVE-2023-34252

An attacker with low privileges and access to the Grav Admin panel can exploit this flaw to execute malicious code remotely, posing a significant risk to the security and integrity of the affected systems.

Technical Details of CVE-2023-34252

This section delves into the specifics of the vulnerability, affected systems, and the exploitation mechanism involved.

Vulnerability Description

The vulnerability resides in the

GravExtension.filterFilter()

function in

/system/src/Grav/Common/Twig/Extension/GravExtension.php

. By circumventing the validation check with array arguments, attackers can bypass security measures and inject harmful templates.

Affected Systems and Versions

The vulnerability impacts Grav versions below 1.7.42. It is crucial for users to update to the patched version to mitigate the risk of exploitation.

Exploitation Mechanism

Attackers can leverage the logic flaw in the

filterFilter()

function to bypass validation checks and inject malicious templates, facilitating remote code execution.

Mitigation and Prevention

To address the CVE-2023-34252 vulnerability, implement the following immediate steps and long-term security practices.

Immediate Steps to Take

Users should update their Grav installation to version 1.7.42 or later to apply the necessary patch. Additionally, ensure that

twig.undefined_functions

and

twig.undefined_filters

properties are set to

false

in the configuration file to prevent Twig from executing undefined functions.

Long-Term Security Practices

It is essential to regularly update Grav and other software components to stay protected against emerging threats. Enforce strong authentication mechanisms and restrict access to sensitive functions to mitigate security risks.

Patching and Updates

Stay informed about security advisories and promptly apply patches released by Grav. Regularly monitor for updates and security announcements to maintain a secure environment.