CVE-2022-25377: Appwrite ACME-challenge Directory Traversal Vulnerability

CVE-2022-25377 refers to a critical directory traversal vulnerability in Appwrite, an open-source end-to-end backend server for web and mobile developers. The flaw affects Appwrite versions .5. to .12.1 and could allow remote attackers to read arbitrary local files, potentially leading to leakage of sensitive information. The vulnerability is found specifically in the ACME-challenge endpoint and requires a certain pathname to be present for the attacker to exploit it. In this post, we will discuss the technical details of the vulnerability, demonstrate how to exploit it, and provide guidance for mitigating and fixing the issue.

Vulnerability Details

The ACME-challenge endpoint in Appwrite is responsible for handling LetsEncrypt certificate verification and installation. When the user chooses to install Let's Encrypt certificates via Appwrite, it automatically creates the vulnerable APP_STORAGE_CERTIFICATES/.well-known/acme-challenge pathname on disk.

The directory traversal vulnerability is caused by insufficient validation of user input. Specifically, an attacker can use "../" to traverse directories and access arbitrary local files on the server. This could potentially expose sensitive information or configuration files.

Exploitation

To exploit CVE-2022-25377, an attacker must send a specially crafted HTTP request to the ACME-challenge endpoint with the "../" directory traversal string. Here's an example of a malicious request:

GET /APP_STORAGE_CERTIFICATES/.well-known/acme-challenge/../some/local/file HTTP/1.1
Host: target_hostname
(Connection and other headers...)

In this request, the attacker is attempting to access "some/local/file" on the server via the vulnerable ACME-challenge endpoint.

Mitigation & Fix

The Appwrite team has released a security patch in version .12.2 that addresses this directory traversal vulnerability. It is highly recommended for all Appwrite users running affected versions to upgrade to the latest version or apply the patch.

Users can find the patch information and detailed instructions for updating their Appwrite installations in the official GitHub repository:

* Appwrite .12.2 Release Notes
* Appwrite GitHub Repository

As a general security practice, Appwrite administrators should also ensure that sensitive files and directories on the server are properly protected using access controls and permissions.

Conclusion

CVE-2022-25377 is a critical directory traversal vulnerability in Appwrite that allows remote attackers to read arbitrary local files on the server. The flaw affects versions .5. through .12.1 and requires the vulnerable ACME-challenge pathname to be present for exploitation.

To mitigate the risk and protect their installations, Appwrite users should upgrade to version .12.2 or apply the security patch provided by the developers. Additionally, server administrators should adhere to best practices for securing sensitive files and directories on their systems.

Timeline

Published on: 02/22/2024 22:15:47 UTC
Last modified on: 02/23/2024 02:42:54 UTC