Cybersecurity Frameworks

Key Management Interoperability Protocol

What is a Wildcard Domain Certificate?

Wildcard Domain Certificate

Table of Contents

What is a Wildcard Certificate?

A wildcard certificate (like SSL/TLS) is a public key certificate that can be used to protect several subdomains inside a domain and is normally acquired from a trustworthy public Certificate Authority (CA).

Multiple subdomains for your website can be beneficial to your business, but they can also be challenging to manage. Multiple SSL/TLS certificates to secure those subdomains increase the complexity, but a wildcard certificate can efficiently resolve this issue.

If compared to managing individual certificates for your subdomains, a Wildcard certificate can save you time and money.

The domain name is prefixed by an asterisk and a period in wildcard notation. Wildcards are frequently used in Secure Socket Layers (SSL) certificates to extend SSL encryption to subdomains. A traditional SSL certificate is only valid for a single domain, such as A * wildcard certificate will also protect,,, and other domains.

How Does Wildcard SSL Certificate Work?

Wildcard certificates are issued to domains with a wildcard character in their hostname, represented by an asterisk (*). This character can represent an infinite amount of subdomains.

Along with your parent domain, a wildcard certificate can secure any number of subdomains.

For better understanding, let’s take an example:

Suppose an organization has three subdomains:


Instead of having three individual SSL certificates for the above subdomains, the organization can purchase only one wildcard certificate. In addition to the subdomains that the wildcard certificate already covers, it can also cover more subdomains without any extra charges.
Wildcard certificates can also be issued as Domain Validated (DV) certificates, which can be provided in a few minutes and require proof of ownership of the domain. You can also get an Organization Validated (OV) certificate, which will include your company’s information in the certificate details. This requires a verification process to ensure that your website is legitimate. But can not be issued as an Extended Validation (EV) Certificate.

Benefits of using Wildcard SSL Certificates

Wildcard SSL certificates can be very beneficial for organizations looking to secure several subdomains while maintaining flexibility. The following are some advantages of using wildcard certificates:

  • Secure any number of subdomains

    Without having different SSL certificates for each subdomain, a single wildcard SSL certificate can cover as many subdomains as you want.

  • Straightforward Certificate Administration

    Individual SSL certificates must be deployed and managed properly to secure an increasing number of public-facing domains, cloud workloads, and devices. But by using a single wildcard certificate, you can manage unlimited domains that make certificate management simpler.

  • Cost-cutting

    A wildcard certificate costs more than an ordinary SSL certificate, but it becomes a cost-effective alternative compared to the overall cost of securing all of your subdomains with their certificate.

  • Fast and Flexible Implementation

    A wildcard certificate is a great way to build new sites on new subdomains that your existing certificate can cover. There’s no need to wait for a new SSL certificate that saves your time and speeds up your time to market.

Overcome your PKI challenges

Risk of Using Wildcard Certificates

Wildcard certificates are frequently used to cover all domains with the same registered root, making administration straightforward. However, because the same private key is used across numerous systems, the freedom that comes with using wildcard certificates also comes with severe security risks:

  • Web Server Security

    If one server or sub-domain gets hacked, all sub-domains may be hacked as well.

  • Access To Private Key

    If the private key of a wildcard certificate gets compromised then the hacker can impersonate any domain for the wildcard certificate.

  • Fake Certificates:

    Attackers can fool a certificate authority (CA) into issuing a wildcard certificate for a bogus organization. Once the attacker gets the fictitious company’s wildcard certificates, they can set up subdomains and phishing sites.

  • Certificate Management

    All sub-domains will require a new certificate if the wildcard certificate gets revoked.

Attackers can easily misuse wildcard certificates if they don’t have adequate security, control, or monitoring.

Let's talk