Security Considerations for Wildcards

While wildcard certificates offer tremendous convenience, they also present unique security considerations. The broad coverage means a compromised private key affects all subdomains simultaneously, potentially magnifying the impact of security breaches. This expanded risk surface requires more stringent key management practices, including secure key generation, restricted access controls, and robust backup procedures. Organizations must weigh convenience against the increased impact of potential compromises.

Key distribution challenges arise when multiple servers or services need the wildcard certificate. Each system requiring the certificate must securely store the private key, expanding the attack surface. Unlike individual certificates where key compromise affects only one service, wildcard key compromise impacts the entire subdomain infrastructure. This risk necessitates careful consideration of which systems truly need the wildcard certificate versus those that could use individual certificates.

Validation limitations affect wildcard certificates, particularly for Extended Validation. EV wildcard certificates don't exist because the EV guidelines require specific validation for each hostname. Organizations requiring EV validation must use multi-domain certificates with explicitly listed hostnames. OV wildcard certificates are available but require the same organizational validation as standard OV certificates. This limitation means organizations cannot use wildcards to achieve the highest trust levels across all subdomains.