The default configuration in Elasticsearch before 1.4.0.Beta1 enables dynamic scripting, which allows remote attackers to execute arbitrary MVEL expressions and Java code via the source parameter to _search. NOTE: this only violates the vendor's intended security policy if the user does not run Elasticsearch in its own independent virtual machine.

References

• https://nvd.nist.gov/vuln/detail/CVE-2014-3120
• https://www.elastic.co/blog/logstash-1-4-3-released
• https://www.found.no/foundation/elasticsearch-security/#staying-safe-while-developing-with-elasticsearch
• http://www.exploit-db.com/exploits/33370
• http://www.rapid7.com/db/modules/exploit/multi/elasticsearch/script_mvel_rce
• https://www.elastic.co/community/security
• http://bouk.co/blog/elasticsearch-rce
• elastic/elasticsearch#7151
• elastic/elasticsearch#7642
• elastic/elasticsearch@bd0eb32
• elastic/elasticsearch@f9de8b6
• https://web.archive.org/web/20140813071419/http://www.securityfocus.com/bid/67731