stuntshell
First of all what powerpoint file types are you actually trying to block, pps or ppt or both or something else as well ??
Looking at the signatures you posted there are differences, but there is no common denominator between pps & ppt files (which I understand are powerpoint files).
To determine the common signature that you can use in the patterns database, you have to test quite a few pps and ppt files, preferably including some created by other users on other systems as well as your own, in order to truly find the common signature.
It appears looking at the examples you quoted that pps and ppt files have a different signature.
.pps file:
0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAAJAAAAZg
.ppt file:
0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAABAAAAAQ
.xls file:
0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAABAAAAGQ
The pattern you entered in the db was this:
0M8R4KGxGuEAAAAAAAAAAAAAAAAAAAAAPgADAP7/CQAGAAAAAAAAAAAAAAABAAAAAQAAAAAAAAAA
which should block the specific ppt file example you tested, but will not block the pps example you tested (or the xls example).
When you say "If I enter de whole pattern, it no longer blocks them:",
this will happen if other ppt file attachments have a different signature.
Did you mistakenly read that this would block pps as it won't.
How many files did you test to determine the pattern ? One is not sufficient as that may not reliably indicate a pattern that will be applicable to all pps files.
As I see it based on the examples you quoted, you will need to have a different pattern for ppt & pps at least.