CVE-2023-31418 - Critical Elasticsearch Vulnerability Leading to OutOfMemory Errors and Node Crashes

Elasticsearch, a popular distributed search and analytics engine, has recently been discovered containing a critical vulnerability leading to OutOfMemory errors and eventual node crashes. Identified as CVE-2023-31418, this vulnerability arises from the way Elasticsearch processes incoming HTTP requests. If exploited successfully, an attacker can force an Elasticsearch node to exit with an OutOfMemory error, all without authenticating themselves.

What is CVE-2023-31418 all about?

An unauthenticated user can exploit this vulnerability by simply sending a moderate number of malformed HTTP requests. This action can potentially bring down the entire Elasticsearch cluster, resulting in service downtime and disrupted operations.

It is important to note that Elastic Engineering, who discovered this vulnerability, has not yet found any evidence of this issue being exploited in the wild or being known publicly. Nonetheless, it is crucial for all Elasticsearch users to be aware of this vulnerability and apply necessary steps to mitigate risks.

A typical HTTP request would look like the following

GET /my_index/_search HTTP/1.1
Host: localhost:920
User-Agent: curl/7.64.1
Accept: */*

However, a malicious actor exploiting CVE-2023-31418 could send a malformed HTTP request such as

GET ////////////////////////////////////////////////////////_search HTTP/1.1
Host: localhost:920
User-Agent: curl/7.64.1
Accept: */*

The exploitation involves sending malformed HTTP requests in such a way that it overwhelms the Elasticsearch node and causes it to crash with an OutOfMemory error.

Original References

For more information about this vulnerability and its implications, users are urged to refer to the following sources:

1. Elastic Engineering Blog Post on CVE-2023-31418
2. National Vulnerability Database (NVD) Entry for CVE-2023-31418

How to Exploit this Vulnerability

_Disclaimer: The following information is for educational purposes only. Users are cautioned not to use this information to perform malicious activities._

An attacker can exploit this vulnerability using a tool such as curl or similar libraries in Python or Node.js. The attacker sends a large number of malformed HTTP requests to the target Elasticsearch HTTP API endpoint, causing the OutOfMemory error to occur.

Elasticsearch users can adopt the following steps to protect their installations from CVE-2023-31418

1. Upgrade to the latest Elasticsearch version: The Elastic engineering team has released patches for this vulnerability in the new version. Upgrading Elasticsearch would be the most effective way to safeguard against this exploit.
2. Limit rate of incoming HTTP requests: Configure a reverse-proxy, such as NGINX or HAProxy, in front of the Elasticsearch HTTP API to limit the rate of incoming HTTP requests from unauthenticated users. This measure could help reduce the risk of being overwhelmed by malicious requests.
3. Regularly monitor Elasticsearch logs: Keep track of incoming HTTP requests and be vigilant for an unexpected pattern of malformed requests. Early detection of such patterns can help prevent any potential exploitation.

In conclusion, it is essential that Elasticsearch users stay informed and proactive about addressing the CVE-2023-31418 vulnerability. As Elastic Engineering continues to learn more about this issue, remaining vigilant and adopting the necessary mitigation measures will ensure that Elasticsearch deployments remain secure and resilient against potential attacks.

Timeline

Published on: 10/26/2023 18:15:08 UTC
Last modified on: 11/06/2023 18:36:24 UTC