Harden OpenSSL Crypto Policy
An XCCDF Rule
Description
Crypto Policies are means of enforcing certain cryptographic settings for
selected applications including OpenSSL. OpenSSL is by default configured to
modify its configuration based on currently configured Crypto Policy.
However, in certain cases it might be needed to override the Crypto Policy
specific to OpenSSL and leave rest of the Crypto Policy intact. This can
be done by dropping a file named opensslcnf-xxx.config, replacing
xxx with arbitrary identifier, into
/etc/crypto-policies/local.d. This has to be followed by running
update-crypto-policies so that changes are applied. Changes are
propagated into /etc/crypto-policies/back-ends/opensslcnf.config.
This rule checks if this file contains predefined Ciphersuites
variable configured with predefined value.
Rationale
The Common Criteria requirements specify that certain parameters for OpenSSL are configured e.g. cipher suites. Currently particular requirements specified by CC are stricter compared to any existing Crypto Policy.
- ID
- xccdf_org.ssgproject.content_rule_harden_openssl_crypto_policy
- Severity
- Medium
- References
- Updated
Remediation - Ansible
- name: Remove configuration from backend file /etc/crypto-policies/back-ends/opensslcnf.config
lineinfile:
path: /etc/crypto-policies/back-ends/opensslcnf.config
regexp: Ciphersuites\s*=\s*.*
state: absent
tags:
Remediation - Shell Script
cp="Ciphersuites = TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256"
file="/etc/crypto-policies/local.d/opensslcnf-ospp.config"
backend_file="/etc/crypto-policies/back-ends/opensslcnf.config"
sed -i "/Ciphersuites\s*=\s*/d" "$backend_file"