Block PDF files via CIFS/SMB

Hi all,

I fear to know the answer but... do you know if there is a way to block PDF files over CIFS/SMB?

I know I cannot use DLP because CIFS is not supported.

I know I cannot use AV because even if in flow mode CIFS is scanned I cannot operate deeper control.

Probably with IPS Custom Signatures? But it's only a guess.

Thanks!