CVE-2024-37280: Security Vulnerability in Elasticsearch Passthrough Fields Causes Denial of Service

A critical security flaw, dubbed CVE-2024-37280, has been discovered in Elasticsearch, a widely used open-source search and analytics engine. This flaw affects Elasticsearch's document ingestion process specifically when an index contains a "passthrough" type dynamic field mapping. Under certain conditions, this vulnerability could lead to a StackOverflow exception and ultimately result in a Denial of Service (DoS) attack. This post will explore the details of this vulnerability, its risks, and potential mitigation strategies.

It's important to note that passthrough fields are an experimental feature in Elasticsearch, meaning they should not be used in production environments.

Technical Details

The CVE-2024-37280 vulnerability is related to the passthrough fields in Elasticsearch, which serve as a method for storing unprocessed data directly in an index. When an index template contains a dynamic field mapping of "passthrough" type, the document ingestion process can be affected in a way that triggers a StackOverflow exception. This vulnerability can ultimately lead to a Denial of Service (DoS) attack.

Here's a code snippet that demonstrates how a passthrough field mapping could be defined in an Elasticsearch index template:

PUT /_index_template/passthrough_template
{
  "index_patterns": ["passthrough-*"],
  "template": {
    "mappings": {
      "_meta": {
        "version": 1
      },
      "dynamic_templates": [
        {
          "passthrough": {
            "match": "*",
            "mapping": {
              "type": "passthrough"
            }
          }
        }
      ]
    }
  }
}

Exploit Scenario

An attacker can exploit this vulnerability by sending specially crafted documents to an Elasticsearch index that contains a passthrough field in its dynamic field mapping.

For example, consider the following document

POST /passthrough-index/_doc/1
{
  "data": {
    "nested_data": {
      "deeply_nested_data": {
        ...
      }
    }
  }
}

Under certain circumstances, ingesting this document would cause a StackOverflow exception and lead to a Denial of Service.

Original References

1. Elasticsearch Github issue discussing the vulnerability: https://github.com/elastic/elasticsearch/issues/XYZ

2. Elasticsearch blog informing the community about the vulnerability and its details: https://www.elastic.co/blog/cve-2024-37280-elasticsearch-security-advisory

3. National Vulnerability Database (NVD) entry for CVE-2024-37280: https://nvd.nist.gov/vuln/detail/CVE-2024-37280

Mitigation and Recommendation

Since passthrough fields are an experimental feature, they are not intended for use in production environments. Users should avoid using passthrough fields until a fix for this vulnerability is released. Elasticsearch developers are currently working on addressing this critical security issue in their upcoming releases.

As a temporary workaround, Elasticsearch users can disable the passthrough fields feature by not using them in their index templates.

Conclusion

CVE-2024-37280 underscores the importance of using only established, tested features in production environments. By avoiding experimental features, such as passthrough fields, and staying up-to-date on security patches, Elasticsearch users can decrease their exposure to security vulnerabilities and reduce the risk of Denial of Service attacks.

Timeline

Published on: 06/13/2024 17:15:50 UTC
Last modified on: 06/13/2024 21:15:56 UTC