CVE-2023-40028: Ghost CMS Path Traversal Vulnerability

CVE-2023-40028 Overview

Ghost is an open source content management system. Versions prior to 5.59.1 are subject to a vulnerability which allows authenticated users to upload files that are symlinks. This can be exploited to perform an arbitrary file read of any file on the host operating system. Site administrators can check for exploitation of this issue by looking for unknown symlinks within Ghost's content/ folder. Version 5.59.1 contains a fix for this issue. All users are advised to upgrade.

Critical Impact
This vulnerability allows for arbitrary file read operations by authenticated users, potentially exposing sensitive data.

Affected Products

ghost ghost
Not Available
Not Available

Discovery Timeline

Not Available - Vulnerability discovered by Not Available
Not Available - Responsible disclosure to ghost
Not Available - CVE CVE-2023-40028 assigned
Not Available - ghost releases security patch
2023-08-15T18:15:10.547 - CVE CVE-2023-40028 published to NVD
2024-11-21T08:18:33.280 - Last updated in NVD database

Technical Details for CVE-2023-40028

Vulnerability Analysis

The vulnerability stems from improper handling of file uploads in Ghost. Users with authenticated access can upload symlink files that may link to sensitive files on the server. This could enable an attacker to access unauthorized data, leading to potential information disclosure.

Root Cause

The vulnerability is caused by inadequate validation of uploaded files, allowing symlinks which can be abused for arbitrary file reads.

Attack Vector

Exploitation requires network access with authentication, where the attacker uploads a malicious symlink file to the Ghost CMS instance.

bash

# Example exploitation code (sanitized)
ln -s /etc/passwd symlink
curl -X POST -F 'file=@symlink' http://vulnerable-ghost-instance/upload

Detection Methods for CVE-2023-40028

Indicators of Compromise

Unknown symlink files present in content/ folder
Unusual file access logs
Suspicious account activity

Detection Strategies

Examine file upload logs for symlinks and validate all files within the content/ directory for unauthorized symlinks. Utilize file integrity monitoring to detect changes or additions of suspicious symlinks.

Monitoring Recommendations

Continuously monitor and validate file uploads and conduct regular audits of the content/ directory. Implement logging to capture file creation and modification activities.

How to Mitigate CVE-2023-40028

Immediate Actions Required

Upgrade to Ghost version 5.59.1 or later
Check for existing symlinks and remove them
Implement stringent file validation mechanisms

Patch Information

The Ghost team has provided a patch in version 5.59.1 that addresses this vulnerability by improving validation of file uploads to prevent symlink attacks.

Workarounds

No known workarounds exist aside from applying the official patch.