CVE-2022-39330 - Nextcloud Server Vulnerability: Performance Degradation Issue Affecting Prior Versions

In this post, we will discuss a recently disclosed vulnerability (CVE-2022-39330) in Nextcloud Server that could be exploited by an attacker to slow down the system, leading to a large amount of database and CPU load. We will explore the affected versions of Nextcloud Server along with the prior versions of Nextcloud Enterprise Server. Furthermore, we will provide details on the exploit, links to original references, and code snippets related to this vulnerability.

Vulnerability Description

Nextcloud Server and Enterprise Server versions mentioned above are vulnerable to a specific performance degradation issue that can be exploited by a logged-in attacker. This issue allows the attacker to send multiple requests that can slow down the system by generating a significant amount of database and CPU load. This increased load can potentially lead to service disruption and reduced functionality for other users.

The vulnerability is specific to the Circles app, which provides features related to groupware functionality for users' circles. Since the problem is tied to this app, it is essential to update Nextcloud Server and the Circles app to resolve this issue.

Log in to the vulnerable Nextcloud Server instance.

2. Send multiple requests to specific vulnerable endpoints of the Circles app, generating an excessive amount of database and CPU load.

// Code snippet illustrating multiple requests

for i in range(100):
    requests.post('https://example.com/nextcloud/apps/circles/vulnerable_endpoint';, data=payload, cookies=cookies)

The code snippet above shows a simple Python script that sends a large number of requests to the vulnerable endpoint on the Nextcloud Server. This script could be used as a starting point to build an exploit script for testing. Please note that this is only an illustration and should not be used for unethical purposes.

Recommended Solution

Nextcloud has already released patches for this vulnerability in the form of updated Nextcloud Server and Nextcloud Enterprise Server versions. Users are advised to update their installations immediately to the patched versions:

Workaround

If you are unable to update your Nextcloud Server or Nextcloud Enterprise Server, disabling the Circles app is a temporary workaround to mitigate this vulnerability.

References

- Nextcloud Security Advisory
- CVE-2022-39330 Details

Remember to keep your Nextcloud Server and its apps up to date to ensure protection against any disclosed vulnerabilities and maintain the security of your platform.

Timeline

Published on: 10/27/2022 14:15:00 UTC
Last modified on: 11/01/2022 13:49:00 UTC