FIPS 140-2

The Federal Information Processing Standard (FIPS) Publication 140-2, (FIPS PUB 140-2), titled “Security Requirements for Cryptographic Modules” is a U.S. government computer security standard used to approve cryptographic modules. Elasticsearch offers a FIPS 140-2 compliant mode and as such can run in a FIPS 140-2 enabled JVM. In order to set Elasticsearch in fips mode, you must set the xpack.security.fips_mode.enabled to true in elasticsearch.yml

For Elasticsearch, adherence to FIPS 140-2 is ensured by

• Using FIPS approved / NIST recommended cryptographic algorithms.
• Delegating the implementation of these cryptographic algorithms to a NIST validated cryptographic module (available via the Java Security Provider in use in the JVM).
• Allowing the configuration of Elasticsearch in a FIPS 140-2 compliant manner, as documented below.

Upgrade considerations

If you plan to upgrade your existing cluster to a version that can be run in a FIPS 140-2 enabled JVM, the suggested approach is to first perform a rolling upgrade to the new version in your existing JVM and perform all necessary configuration changes in preparation for running in fips mode. You can then perform a rolling restart of the nodes, this time starting each node in the FIPS 140-2 JVM. This enables Elasticsearch to take care of a couple of things automatically for you:

• Secure settings will be upgraded to the latest format version as previous format versions cannot be loaded in a FIPS 140-2 JVM.
• Self-generated trial licenses will be upgraded to the latest format that is compliant with FIPS 140-2.

If you have a subscription that supports FIPS 140-2 mode, you can elect to perform a rolling upgrade while at the same time running each upgraded node in a FIPS 140-2 JVM. In this case, you would need to also regenerate your elasticsearch.keystore and migrate all secure settings to it, in addition to the necessary configuration changes outlined below, before starting each node.

Configuring Elasticsearch for FIPS 140-2

Apart from setting xpack.security.fips_mode.enabled, a number of security related settings need to be configured accordingly in order to be compliant and able to run Elasticsearch successfully in a FIPS 140-2 enabled JVM.

TLS

SSLv2 and SSLv3 are not allowed by FIPS 140-2, so SSLv2Hello and SSLv3 cannot be used for ssl.supported_protocols.

The use of TLS ciphers is mainly governed by the relevant crypto module (the FIPS Approved Security Provider that your JVM uses). All the ciphers that are configured by default in Elasticsearch are FIPS 140-2 compliant and as such can be used in a FIPS 140-2 JVM. See ssl.cipher_suites.

TLS Keystores and keys

Keystores can be used in a number of General TLS settings in order to conveniently store key and trust material. Neither JKS, nor PKCS#12 keystores can be used in a FIPS 140-2 enabled JVM however, so you must refrain from using these keystores. Your FIPS 140-2 provider may provide a compliant keystore that can be used or you can use PEM encoded files. To use PEM encoded key material, you can use the relevant \*.key and *.certificate configuration options, and for trust material you can use *.certificate_authorities.

FIPS 140-2 compliance dictates that the length of the public keys used for TLS must correspond to the strength of the symmetric key algorithm in use in TLS. Depending on the value of ssl.cipher_suites that you select to use, the TLS keys must have corresponding length according to the following table:

Table 72. Comparable key strengths

Password Hashing

Elasticsearch offers a number of algorithms for securely hashing credentials in memory and on disk. However, only the PBKDF2 family of algorithms is compliant with FIPS 140-2 for password hashing. You must set the cache.hash_algo realm settings and the xpack.security.authc.password_hashing.algorithm setting to one of the available PBKDF2 values. See User cache and password hash algorithms.

Password hashing configuration changes are not retroactive so the stored hashed credentials of existing users of the file and native realms will not be updated on disk. Authentication will still work, but in order to ensure FIPS 140-2 compliance, you would need to recreate users or change their password using the elasticsearch-user CLI tool for the file realm and the create users and change password APIs for the native realm.

The user cache will be emptied upon node restart, so any existing hashes using non-compliant algorithms will be discarded and the new ones will be created using the compliant PBKDF2 algorithm you have selected.

Limitations

Due to the limitations that FIPS 140-2 compliance enforces, a small number of features are not available while running in fips mode. The list is as follows:

• Azure Classic Discovery Plugin
• Ingest Attachment Plugin
• The elasticsearch-certutil tool. However, elasticsearch-certutil can very well be used in a non FIPS 140-2 enabled JVM (pointing JAVA_HOME environment variable to a different java installation) in order to generate the keys and certificates that can be later used in the FIPS 140-2 enabled JVM.
• The SQL CLI client cannot run in a FIPS 140-2 enabled JVM while using TLS for transport security or PKI for client authentication.