Defining Custom Detection Rules
Security for Confluence allows for creation of custom scanning rules using regular expressions.
Only Confluence Administrators can access these settings.
To create a rule, first visit the Settings page, and then expand the “Custom rules” section.

Our application uses the built-in JDK java regex library (Java 8), which you can compare to other regex engines here.
Security for Confluence imposes hard limits on how much memory a rule can use and how long a rule can take to scan a page fragment. Scanning rules which exceed these limits will be automatically disabled, and the scan will be marked as failed.
If a secret in a single page fragment matches more than one rule (built-in or custom), only the first match will be reported.
Here are some example rules:
Bitcoin Address
^[13][a-km-zA-HJ-NP-Z0-9]{26,33}$
Youtube Links
<a\s+(?:[^>]*)href=\"((?:https|http):\/\/\w{0,3}.youtube+\.\w{2,3}\/watch\?v=[\w-]{11})">(?:.*?)<\/a>