the idea would be (for massive databases such as known good hashes) to have a module that would - on attribute view - pass values of certain types of attributes to a fast query system and check whether the value exists. If yes, add a warning.
Practical example: NSRL
Another example that would benefit from this, it's an automatic geographical lookup using the Maxmind local database to have a complete view of all geographic localization when viewing an event. There is not a warning but a list of results to display.
Most helpful comment
Practical example: NSRL