SSL certificate audit

    1. What is it?

SSL certificate audit is a new feature available for Enterprise customers which runs tests to detect phishing and null prefix attacks. The main goal is to provide you with a detailed overview of your assets, as well as an information who is the certificate issuer so that you can be sure no fraudulent certificates are being issued, and if they are - react on time and prevent your users from being tricked by them.

    2. How does it work?

The audit is based on analysing publicly available records from SSL transparency logs and searching for certificates issued for malicious domains that look similar to your domain.

The current feature is only looking for the newly issued or updated certificates coming from the Certificate Log Update Stream (it is not looking for e.g. Certificate Revocation Lists). We use to listen to a real time stream of logs.

a). In the first place, our Certificate Monitor listens in to all the incoming certificates. 

b). Next, the Certificate Matcher cross-validates the incoming certificates with the client's existing assets and checks if any certificate is issued to any subdomain of existing domains. Once the certificate has been found and it matches the existing subdomain, it is used to populate the Asset Catalogue (previously called Asset Inventory). 

c). The Certificate Audit component checks for the vulnerabilities. In the current release the Certificate Transparency Tests focus on:

  • Null prefix attacks

  • Phishing attacks

The future releases will include subcategories of phishing attacks: typo- and bitsquatting attacks.

    3. Certificate Transparency Tests in detail:

a). Null prefix attack: 00 (\0) is added to the domain name to mask remaining content

b). Phishing attack: domain name is similar to existing domain name

  • homoglyph (e.g.: or

  • TLD difference (e.g.:

  • name similarity using Levenshtein comparison (e.g.:

    4. How to turn the feature on?

The Autodiscovery part is already running in the background - the findings will keep populating your Assets Catalogue. 

The Cert Auditor vulnerability check is something you opt in for - it can be enabled or disabled in your Surface Monitoring Advanced Settings:

Go to your Assets and select your root asset. You will then be forwarded to your Asset Overview where in the top right corner you will see the Surface Monitoring Advanced Settings.

SSL Certificate Audit is off by default, mark it and click on the "save" button to turn it on.

    5. Where can you see the findings?

Domains that have been auto-discovered by Cert Matcher will be visible in your Asset Catalogue. 

Findings produced by Cert Audit will be visible in your Surface Monitoring Results.