Your certification authority (CA) is a key component in securing your network. It is the entity that issues, manages, and verifies digital certificates across your PKI (public key infrastructure). Using certified public and private keys, a CA offers a higher level of verification than common authentication techniques. It ensures that your hardware and software systems are securely communicating with legitimate entities. To help you secure your network assets and confidently interact with third-party servers, you should use root CA security best practices.
Without using properly configured CAs, a network of systems will fall under increased threat from man-in-the-middle attacks or other threats that seek to intercept your communications by impersonating public sources. Sitting at the top of your PKI hierarchy is the root CA. It is trusted by all other assets and users in your organization, generating a self-signed root certificate. As such, taking steps to maintain the veracity and secrecy of your root private key is of the utmost importance.
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Private Key Protection
Hardware Security Module (HSM) is recommended to protect the CAs private key. HSMs can either be directly attached to the CA or attached via a private network connection. It’s almost never recommended to directly connect a CA with your network as it will result in an increased risk of attack on the CA host machine or OS.
Regardless of whether you are using an HSM or not, you should establish a chain of custody and conduct a key signing ceremony. Physical access, such as USBs and CD-ROM auto-play should also be used cautiously, if at all.
Keep the Root CA Offline
Using offline root CA storage can provide an extra layer of physical protection on top of other logical security measures. Today, you can find specialized Secure Cryptographic Devices made exclusively for the purpose of securely storing root CA private keys offline.
Using this method, a subordinate CA generates requests that it sends to the offline root CA to sign using its private key. During the actual signing process, the root CA system is kept offline to prevent any tampering or illegitimate access.
RDPs (remote desktop protocol) and other access technologies to the offline root CA should be limited. The machine should only be brought online for maintenance, updates, or to produce a new CRL. Only the CA Administrator should have access to the root CA.
Document and Audit CA Retrieval
Whenever a certificate is authenticated, generated, or retrieved in conjunction with the root CA, the process should be audited and documented. This is also referred to as establishing the chain of custody or key signing ceremony.
In the event that your CA has been compromised in any way, this will help you identify which areas have been affected. In addition, it helps to establish a forensic trail to reestablish normal operations and address any damages. This may also be crucial for maintaining compliance with certain security and data protection regulations.
Auditing can generally be enabled within the root CA settings itself as well as in the operating system.
Other Best Practices for securing your root CA
Aside from the above physical implementations to secure your root CA, you should also maintain certain operational standards and policies:
Multi-role supervision: Enforce that accessing and using the root CA for signing certificates requires supervision from multiple security roles within your organization.
Operate on the assumption of least privilege: All roles, even administrators, should only have access to the minimum data required to execute their assignments.
A compromised root CA can lead to a loss of trust down your entire certification hierarchy. Additionally, ot can cause serious compromise of the security across your network. Not having best practices and policies in place to minimize threats to your CA can also leave you open to additional scrutiny from regulatory and compliance bodies.
However, too many organizations still lack the knowledge and initiative from their stakeholders to take these steps. These solutions can also be complex to configure or implement, requiring a skillful and practiced hand. That’s why it’s important to work with a trusted and experience partner like LIFARS when proactively securing your CA.
Security Best Practices for Offline Certification Authorities