In Data Loss Prevention, for a response rule, can you use a regex expression in the file name under the "File Properties" - "Message Attachment or File Name Match" condition.
No, regex is not supported.
For file name matching, the system supports the DOS pattern matching syntax to detect file names, including wild cards.
Any characters you enter (other than the DOS operators) match exactly.
To enter multiple file names, enter them as comma separated values or by line space.
The following operators are allowed in the file name:
For more information, see the "File name matching syntax" section of the Data Loss Prevention Administration Guide.
Symantec Data Loss Prevention Administration Guide
This applies to all version up to the current version, 15.5.
This may change in future versions.
Refer to the latest Data Loss Prevention Administration Guide.