This topic describes how to search for file extensions.

With the filemod_name field, it is common to use a leading wildcard regex to find all executable writers in a time window. For example:
filemod_name:/.+\.exe/

Because file extensions are tokenized on their own, you do not need to use a regex or wildcard for this type of search. filemod_name:.exe works. Platform Search breaks down the terms to make most searches possible without the need for leading wildcards.